Larry Rasmussen’s Lecture for the Bonhoeffer Lectures in Public Ethics at Union Seminary

Voices from science, ethics, and theology on Eco-Reformation.

Veni, Creator Spiritus!
An Ecological Reformation

Veni, Creator Spiritus! Once a World Council of Churches program theme, “Come, Holy Spirit, renew your whole creation!” surfaced again in an ecumenical gathering in Greece in March 2016, this time as a “Manifesto for an Ecological Reformation of Christianity.” The authors note the Reformation Jubilee of 2017 as the opportune moment for the manifesto. The backstory is the urgent call of Christians from areas most vulnerable to the constellations of economic power, whether in the Pacific, Africa, Asia, Latin America, or from minority populations in Europe and North America. Add the Pope’s ringing encyclical, Laudato Si’ , and Protestant countries in the North keenly aware of the environmental degradation of their consumerist life style, and we have an ecological cry that is as clear, strong and emphatic as Beethoven’s Ninth.

But that an ecological reformation must take place in order to spare calamity does not mean it will. Like Luther’s own movement, a reformation requires a certain constellation of events and powers together with critical technology (for Luther, the printing press) at a certain burning point in history.

So are we there yet? I feel like answering the Psalmist’s “How long, o Lord, how long? with “Not long, not long.” But I say that with my fingers crossed. That the Trump administration is narcissistic nationalistic white male billionaire fossil-fueled rule barreling full-steam ahead into the 19th c. is a direct body blow to any eco-reformation.

Nonetheless, we are there already in that hard planetary reality is our daily fare and prophetic voices are clear. I turn to three such voices—from science, ethics, and theology—to make the case. That Dietrich Bonhoeffer anticipated most of it is the wonder I’ll note later.

Science. “I arise in the morning torn between a desire to save the world and a desire to savor the world. This makes it hard to plan the day.” If you thought E. B. White was right, that torn between a desire to fix the universe and a desire to kick back and enjoy it makes it hard to plan the day, try taking the geologist’s perspective, or the astrophysicist’s. In geological perspective, we are not a whole lot more than “fossils in the making, to be buried and eventually exposed again for the puzzlement of creatures of later eras.”

The astrophysicist dismisses even the geologist’s grand field of view as quaint. Okay, accommodate the geologist, skip the first 10 billion years of the universe, and fast-forward to Earth’s appearing. Then conceive Earth’s history as a 10-volume set in the Burke Library, with 500 pages per volume. If we do that, each page tells the tale of 1 million years. Life, any life, first makes its appearance in Vol. 8. That volume is mostly about plants, but on p. 440, reptiles have a good run, only to be superseded by birds and warm-blooded animals 5 pages on, i.e., about 5 million years later. On p. 499 of the very last volume, no. 10, hominids appear, the homo sapiens among them probably making claims to “dominion” and surmising that the drama of the previous 13.8 billion years of cosmic history is, in the end, all about us. Never mind that the story of human civilization is only the last two or three words of the last page of the last volume. In Big History all of human history is a late case of spontaneous combustion. Who are we? We are fossils in the making, afloat on a miniscule “mote of matter” in God’s creation, living a puny moment. That makes it hard to plan the day.

Don’t get me wrong. The astrophysicist will also leave you lost in wonder. She’ll explain that the calcium in your teeth and the iron in your blood are detritus of exploded stars from a galaxy long ago and far away. Like everything else, you are immortal stardust. Relish it. Hear a portion of Maya Angelou’s poem, “A Brave and Startling Truth”:

We, this people, on a small and lonely planet
Traveling through casual space
Past aloof stars, across the way of indifferent suns
To a destination where all signs tell us
It is possible and imperative that we learn
A brave and startling truth.
When we come to it
Then we will confess that not the Pyramids
With their stones set in mysterious perfection
Nor the Gardens of Babylon
Hanging as eternal beauty
In our collective memory
Nor the Grand Canyon
Kindled into delicious color
By Western sunsets
Neither Father Amazon nor Mother Mississippi
who, without favor,
Nurture all creatures in the depths and on the
These are not the only wonders of the world
When we come to it
We, this people on this miniscule and kithless
Who reach daily for the bomb, the blade and the
Yet who petition in the dark for tokens of peace
We, this people, on this mote of matter
In whose mouths abide cankerous words
Which challenge our very existence
Yet out of those same mouths
Come songs of such exquisite sweetness
That the heart falters in its labor
And the body is quieted into awe
Out of such chaos, of such contradiction
We learn that we are neither devils nor divines
When we come to it
We, this people, on this wayward, floating body
Created on this earth, of this earth
Have the power to fashion for this earth
A climate where every man and every woman
Can live freely without sanctimonious piety
Without crippling fear
When we come to it
We must confess that we are the possible
We are the miraculous, the true wonder of this
That is when, and only when
We come to it.

I love the comment of Robin Nagle, an anthropologist at the New York City Department of Sanitation. (Where but New York does the Dept. of Sanitation have a house anthropologist?) Robin says, “Everything is garbage and everything is sacred.” Think about it. It is all garbage—everything we know about this “miniscule and kithless globe” (Angelou) and its life is recycled stardust. And if you pass your days in a sacred universe, then all this garbage is sacred. Pure wonder.
But the astrophysicist’s and geologist’s perspective, Maya Angelou’s and Robin Nagle’s, does make it hard to plan the day.

The current message of science doesn’t make it easier. It’s another “brave and startling truth.” Namely, that we humans—we the possible, the miraculous, the true wonder of this world—are, for the first time ever, a geological force, creators of an epoch already dubbed “the Anthropocene,” so-named because collective human activity now dominates the workings of the planet.

But because this colossal domination has never before happened on our watch—our three-word tenure in Vol. 10 is strictly late Holocene—we need to know what happens when Planet Home wanders from one geological epoch into another.

Two things occur. Both need a note on language, language about “law” and about “climate.”

I live in Santa Fe, bumper sticker capital of the world. One reads: “Gravity is not only a good idea. It’s the law.” This kind of law cannot be repealed. It’s the kind Naomi Klein refers to in the stand-off she describes: “[O]ur economic system and our planetary system are now at war. Or, more accurately, our economy is at war with many forms of life on earth, including human life. What the climate needs to avoid collapse is a contraction in humanity’s use of resources; what our economic model demands to avoid collapse is unfettered expansion. Only one of these sets of rules can be changed, and it’s not the laws of nature.” So if you raise the temperature to a certain fixed point, water as ice becomes liquid, whatever your intention or means. It’s not just a good—or bad—idea. It’s the law, a law not subject to amendment by the EPA or repeal by climate and science skeptics.

“Climate change” also needs a note. As a phrase it’s misleading. Science is more precise. It’s not changes in climate per se. With variations in weather and its long-term trends, climate change is always happening. It’s “changes in the climate system” that science records and underscores. For example, “the rate of CO2 growth over the last decade is 100 to 200 times faster than what the Earth experienced during the transition from the last Ice Age,” and the present 405.1 parts per million is the highest its been in more than 10,000 years. Or, if we look from that “elegant creature,” the atmosphere (Wendell Berry), to another elegant creature, the oceans, we find that roughly half the coral reefs are bleaching and/or dying. Coral reefs are only 0.2 percent of the ocean floor but they are its nurseries and they support one-quarter of all marine life. They are victims of more rapid acidification than has transpired in 8 million years. Weep for the reefs or, as Jesus tells the daughters of Jerusalem in Luke 12: 28, “Weep not for me, but weep for yourselves and your children.”
The point of this and more—record warming, record drop in Arctic and Antarctic sea ice, record high sea levels, severe drought and deluge, etc.—is Earth-shaking climate system change. Climate system change is the first reality that nudges one geologic epoch into another. It’s the law.

The second transforming reality is drastic change in the community of life. The diversity of life forms—biodiversity—is the repertoire that allows eventual adaptation to different conditions, including the upended conditions that yield mass extinctions. Speaking of which, mass extinctions, like new geological epochs, are very rare. There have been but five in the 3.5 billion years Earth has known life. Until now. We are apparently logging in the Sixth Great Extinction, this the first one brought on by human powers destructive of natural habitat and fined-tuned environments. Life can fall from its perch—or be pushed. We are pushing.

In sum, a new geological epoch turns on dramatic climate system change and dramatic change in biodiversity. For us this means that the long-standing natural chemical balance beneficial to human life in the late Holocene, with its tattoo of climate stability, has been altered by an exploding human population and by an exploding extractive economy driven by fossil fuels. So altered that the Anthropocene’s tattoo is apparently climate volatility, mass eco-social uncertainty, and a die-off some scientists fear will exceed 50% of known species. A single species, ours truly, is a disaster for planetary systems.

You can state the conclusion the way the World Meterorological Organization does: “Earth is a planet in upheaval” with humanity “now in truly uncharted territory.” Hold on to that for our discussion of ethics and theology.
Here’s the next “brave and startling truth.” We do need to plan our day, and we need to do it in changing geological time, “in truly uncharted territory.” How do we live within unprecedented geological, chemical and biological processes when all life, ours included, depends upon them? How do we live when we are the single most decisive force of nature itself and nature has changed course as a consequence?

Such power flows from the daily choices and actions of our way of life. That makes those choices, actions and way of life ipso facto ethical matters. You may not think of your breakfast, your shower, your commute, your job, and shopping as leading moral issues. But on a human-dominated planet, diet and agriculture, water, energy, work, and consumerism are macro moral issues, even justice issues, whether breakfast and bananas register with you as one of them or not.
We have the numbers. Dirk Notz and Julienne Stroeve have the calculations that show how much Arctic sea ice melts for every ton of CO2 sent into the atmosphere. About three square meters. So the last 1000 miles you drove a car, or the round trip flight you took from Kennedy (New York) to Heathrow (London), caused 32 square feet of sea ice to vanish from the Arctic. And that’s only the drive or the flight, not breakfast, lunch or dinner. The Arctic pays extra for those. In the Anthropocene there is no such thing as a free lunch. It’s the law.

Decades ago a British newspaper invited readers to write in their answer to the question, “What’s wrong with the world today?” Here’s one reply: “Dear sir, I am. Yours, G. K. Chesterton.”

Ethics. We already hear the second voice—the ethicist’s.

Of utmost import for ethics is that climate system change, mass extinction, and sour oceans is anthropogenic geophysical change that goes where human agency and responsibility have never before gone. Namely, to cite Willis Jenkins, “cumulatively across generational time, aggregately through ecological systems, and nonintentionally over evolutionary futures.” This is a seismic shift in human impact for which we have little ethics on the books or in common moral practice, with the important exception of some indigenous peoples. Cumulative human consequences far exceed the time and space dimensions of past and present accountability. That is the moral novelty of the Anthropocene.
Jenkins himself wonders whether this novel reach outstrips even our capacity to “do” ethics, i.e., to meaningfully assign responsibility for the powers we wield. He writes: “This is the greatest peril of climate change: that the accidental powers of humanity generate problems that exceed our moral imagination and defeat our abilities to take responsibility.”
Let me illustrate. Every full-bodied ethic attends to three matters. To character—the kinds of persons and societies we are (virtue); to the consequences of how we live; and to our moral bottom lines—the fundamental obligations that structure our moral universe.

Take only the second of these. When the consequences of how we live match the boundaries of the ecosphere (the full community of life and its abiotic envelope) and stretch into futures we heavily determine, but cannot know, or even imagine, how do we take those futures into account as we make present decisions? If, to recall Jenkins again, our on-the-ground agency works its way “cumulatively across generational time, aggregately through ecological systems, and nonintentionally over evolutionary futures,” how do we organize breakfast, the kids’ education, or the global economy so as to account for eventual consequences in what are vast, complex, non-linear systems? An ethic of consequences has no way to measure and assign responsibility when our reach exceeds our horizons and a stable planet can no longer be assumed.

Assigning responsibility was already difficult enough for our most significant actions, channeled as they are through large interacting systems. It borders on impossible to trace these to individuals. Instead they involve many persons who are not in conscious touch with one another and who are unaware of the collective impact of their coordinated actions. (We mentioned breakfast and commuting to work above, affecting agriculture, energy and the atmosphere.) The global supply line of responsibility is effectively invisible. And if there is structural violence along the way to workers and environment, say, it is rarely criminalized.

While we could talk about the novelty for anthropocene ethics of virtue and obligation as well, for now I move to a vital factor that stands apart from novel conditions.

The landmark Brundtland report of 1987, Our Common Future, says “the Earth is one but the world is not.” Any eco-Reformation can only begin, like Luther, with realities as they are on the ground. “The Earth is one.” This is true as a statement of both scientific and biblical truth. “[B]ut the world is not.” This, too, tells the truth. So how do we respond to the histories that brought us to the present, and how do we do so in view of our anthropocene powers? Two matters command attention.

The first is the narrative that yields the planetary emergency. It’s the grand narrative of mastery. Climate system change and climate injustice are chapters in the epic story of oppression—oppression of people and oppression of the rest of nature, together (inevitably). The sources are not with ignorant peoples or conquered peoples. This oppression is largely the result of work by people with BAs, BSs, LLBs, MBAs, and PhDs. It’s the result of mastery based in a highly sophisticated “combination of scientific knowledge, technological control, and narratives that position Western societies as the rightful stewards of natural and social progress.” It results from the way so-called advanced industrial civilization organizes and feeds itself. It issues as well from the illusion that what we create we also control. Climate system change mocks that premise.

The seeds of the mastery now geo-engineering Earth are in European and neo-European cosmology, conquest, colonization, commerce, and Christianity, trumpeted together as superior civilization with a mission, a mission to bring others to salvation and into modernity. Baptized “the march of progress” in the 19th and 20th centuries, in the 20th century it was re-named “development.” Now it’s morphed into “sustainable development.” Sustainable development is the economy of green consumerism based in the scientific and technical expertise of the Global North over the Global South. Globe-spanning corporations fuel this consumerism.

Let me say this differently. Morality and ethics in our time has “not been cooperatively produced,” however much we tout democracy as we practice plutocracy and kleptocracy. Yes, huge strides have been made—the abolition of legal slavery, universal human rights, and social justice victories in recurring battles with the barons of industry and finance. But present institutions remain deeply embedded in the continuing power of their origins in white supremacy, patriarchy, and capitalism. The people in the back offices and on the global supply lines may not be white and paternal—they probably are not—but their institutions and practices are. Yes, the mastery model now threatens destruction on every side, blandly called “unsustainability.” And yes the stage has been set for the politics of resentment, anger, backlash and fear of the threatening “other,” all of it wrapped in the normative stories and desperate hopes of American exceptionalism and greatness. People don’t act on the basis of data sets and facts; they act on stories. And we are reaping the whirlwind of a story that presently yields a triple crisis, the crisis of morality, of democracy, and of the planetary environment.
So how do we plan our day? The best way to address anthropocene injustices is by dismantling white privilege, male privilege, and wealth, or class, privilege as these drive a human economy destructive of nature’s economy and the well-being of billions of people.

I’m sorry this agenda is old and tired rather than new and invigorating. The way forward, at least for most white people, is repentance, renewal, and repair (reparations).

James Baldwin is the guide. In The Price of the Ticket he writes of “do[ing] our first works over”:

In the church I come from—which is not at all the same church to which white Americans belong—we were counseled, from time to time, to do our first works over. Go back to where you started, or as far back as you can, examine all of it, travel your road again and tell the truth about it. Sing or shout or testify or keep it to yourself but know whence you came.6

To do white “first works over” means to reexamine everything from its onset, speak the truth as best one can, change the normative gaze and controlling narrative of this way of life, and re-do and re-purpose its institutions.
Yet this daunting agenda is new in a critical way. It is new because our cumulative powers range across the whole ecosphere and into the homelands of distant generations. The eco-Reformation task, then, is to connect “multiple social worlds to a shared view of human and Earth histories” and to find alliances for the long haul good of both people and the planet.

So what is left of conventional ethics? How do we start with what we have and move from there into viable moral imagination and practice?

We start with social justice, now more urgent than ever. But if it is not enhanced as creation justice, even social justice cannot be sustained. Human health on a degraded planet is oxymoronic. The Salish wisdom, “We are as alive as the Earth is alive,” has as its counterpoint that, for a big human world on a small planet, we are as injured, ill, or dead as Earth is.

That means changes in basic obligations. Commitments to family and democracy remain. But we can’t keep even these if we don’t invert the assumptions of industrial civilization. Thomas Berry has the relationship right: “Planetary health is primary; human well-being is derivative.” Because human well-being is derivative, planetary health is primary.
Likewise, the first law of economics is preservation of nature’s economy. The human economy is, and always has been, derivative.

The same holds for energy. Most justice attention to energy asks questions such as: Do we have enough to grow the economy to meet human needs? Are we energy-independent? How will energy be distributed fairly? These discussions all go on without first asking what sources and uses are mandated by the planet’s climate-energy system, the way in which it regulates the incoming solar heat that makes life possible and keeps Earth from being a frigid rock and no more. Our common questions assume that human energy use is primary. This is exactly backwards. The first law of energy is preservation of the planet’s climate-energy system as conducive to life; human energy use is derivative of the planet’s. It’s the law.

Or consider the ethics of virtue. Standard virtues remain indispensible—honesty, trustworthiness, solidarity, love, empathy and compassion. But if they are not joined to Maya Angelou’s, Thomas Berry’s, Wendell Berry’s, and Martin Luther’s sense of wonder, awakening awe, humility and what Martin Luther King called “cosmic companionship,” and “the sacredness of all human life” and we will not exit the deadly arrogance of ourselves as master, with the rest of nature slave.

Theology. I finish with the witness of Dietrich Bonhoeffer. In his theological letters of 1944, Bonhoeffer traces the arrival of a new epoch. Naming it the “world-coming-of-age,” it is the rise of unprecedented human powers. These powers compel a new ethic of responsibility.

This novel historical development solidifies Bonhoeffer’s resolve to finish his magnum opus, Ethics. He had already tried several approaches. None, however, was completed to his satisfaction. Then, landing on our time as unprecedented human knowledge and power in all domains, he realizes he will need to rethink it all, taking stock of everything. He knows that the world-come-of-age powers we’re calling anthropocene powers lack a viable faith and ethic to guide them. He also knows the deadly past cannot be the future. He had located the fatal flaw in 1932, even before Hitler. Namely, an aggressive “war-and-industry” identity that has its sources in the West’s battles “to master nature, fight against it, to force it to its service.” This assertive mastery, he says, is “the fundamental theme of European-American history.”
But this is not only a battle against non-human nature. It is also a battle “against other human beings.” “In the most essential sense his life means ‘killing,’” Bonhoeffer says of the European.

In sum, Euro-Western civilization, fragmented from the rest of nature in its core consciousness and practices, destroys natural and human communities together in an exercise of collective power with few spiritual and moral constraints. This is mastery that knows no limits as undertaken by autonomous humans in the name of freedom without constraint.
All this Bonhoeffer knew in 1932. Now jump to 1944 and connect it to the new book he needs to write before he can return to Ethics. Here is part of his outline:

…[The West’s] goal is to be independent of nature. Nature used
to be conquered by the soul; with us it is conquered through
technological organization of all kinds. What is unmediated for us, what is given, is no longer nature but organization. But with
this protection from the menace of nature, a new threat to life
is created in turn, namely, through organization itself. Now the
power of the soul is lacking! The human being is thrown back on
his own resources. He has learned to cope with everything except himself. He can insure himself against everything but other human beings. In the end it all comes down to the human being.

The reach of this human knowledge and power across all earthly life, throwing everything back upon ourselves, has strained standard ethical concepts to the breaking point, Bonhoeffer says. Moral imagination and responsibility require redoing. And while that is the subject of Ethics, no way forward is possible that would bypass theo-ethical foundations and their imposing historical context. To start with, there is no dialing back of history to some previous age, including the age of a human religious a priori and the God of religion. For Christians, this means that any constructive work interrogates faith’s most essential base points. Who is God, Bonhoeffer asks, and what do we really believe such that we would stake our lives on it? What do the key base points—“creation, fall, reconciliation, repentance, faith, vita nova, last things,” mean now? Who is Jesus Christ for us today when “today” is a different epoch, even a non-analogous one?

The greatly expanded knowledge and power is epistemological as well as theological and moral. It need not posit God as necessary to advancing either knowledge or power, and does not turn to a parental God for a bail-out when that knowledge and those powers fail, as they do and will. Here resides Bonhoeffer’s critique of religion. The God of this new moment will not be God as a working hypothesis, the God-of-the-gaps. To do what humans do, science doesn’t need this God, and neither do we. Nor will this be the rescuer God, God as deus ex machina. Not only can responsible persons get along quite well without these particular “Gods,” but turning to them in a time of greatly expanded powers is a moral cop-out. The God-of-the-gaps and the rescuer God belong to the religion of an earlier consciousness and era. It may well have been the consciousness of nineteen hundred years of Christianity, Bonhoeffer says, but as practiced now, that religion is dysfunctional as genuine discipleship. In an epoch we now recognize as an era of planet-changing human power, “claiming Christ” for “a world-come-of-age,” or answering the question, “Who is Jesus Christ, for us, today,” requires another course, one that will confront human power and knowledge so as to find God in what we do know, rather than in what we don’t, and in problems that are solved, rather than only when and where we are vexed. Moral accountability and confession of sins will address the sins of our strengths and powers, rather than our weaknesses only. If God and standing before God in the Anthropocene cannot be located at the heart of human power, accountability, accomplishment and failure, then God and morality are pushed to the margins of all that truly counts for the life of the world. They are beyond the “pale” in the literal sense of that word; namely, beyond the “bounds” or “region” or “tract” of lived human life and accountability.

Bonhoeffer has already provided the contrast: “Before God and with God we live without God.” Or, in another formulation: We live etsi deus non daretur (as though God does not exist). I.e., before the God of world-come-of-age powers and with this God, we live without the God of religion. We live with the God who empowers humans to take full responsibility for their unprecedented powers. God does not win space in the Anthropocene by virtue of omnipotence and rescue, but by entering into suffering in the way of Jesus, bringing life to the wounded and broken places, nature’s included. So, too, is the exercise of our responsibility in a world where all turns on humanity. Before and with this God we live without the God of religion and without our pre-world-come-of-age consciousness.

To close I cut to the chase. Having heard the voices of science, ethics, and theology, what does a “Manifesto for an Ecological Reformation of Christianity” include, at least if you want a life where collateral beauty surpasses collateral damage?

It includes chutzpah of a particular kind, the sort articulated by Joan Chittister: “Life comes out of death. The present rises from the ashes of the past. The future is always possible for those who are willing to re-create it.” If you’re not ready for death and resurrection, don’t sign up.

At least for those of us formed by industrial civilization, it includes a new relationship to the planet and its peoples. While we will always be tribal because of human limitations—our horizons are inherently limited and our close connections always numbered—the planet is “getting too small for both an Us and a Them.” “We have no separate fates”…We are “fixed to one another.” It’s the law; get used to it. So while we cannot avoid being tribal, neither can we afford being tribal only. There will always be others; but they need not be enemies. Apartheid “othering” is out.

As part of a new relationship to the planet and its peoples, “an Ecological Reformation” is far more than recycling bins, “green” prayers, a call for responsible stewardship, and a recovered theology of creation. This reformation “calls for a rereading of the canonical biblical texts, a critique of the environmental impact of specific Christian traditions and practices, a retrieval of historical insights, figures and practices, a reinvestigation of the content and significance of the Christian faith, a reconsideration of influential symbols, a renewal of Christian communities and a transformation of the ministries and missions of the church. The ecological reformation of Christianity therefore is comprehensive in its scope and needs to extend to Bible study, catechism, teaching, liturgies, hymns, Christian art, pastoral care, ministry and mission alike,” including public witness and practice.

It will include resistance and polemics. If you don’t like either, ditch Luther, Calvin, Zwingli, Simons, Fox, Frederick Douglass, Ida Wells-Barnett, Dorothy Day, Martin Luther King, Malcolm X, and Pope Francis. Reformation means theological and moral resistance and polemics against white supremacy, patriarchy, our kind of economy and their underpinning cosmology, theology and morality.

At the same time, resistance must be matched to reconstruction. For that, collaboration with civic and governmental entities is essential, even when tense. Learn the hard lesson from Bonhoeffer that, in a world of wicked problems, everyone who acts responsibly will become guilty. Learn from Niebuhr that the question is not the purity of our motives, but the integrity of our compromises. Learn from Black Lives Matter that while the content of our character matters, the character and content of our institutions matters even more. And may we all honor the Great Commandment by learning to love ourselves so fiercely that we change.

The ecological reformation also includes communal joy. It’s “life together” (Bonhoeffer). You may not appreciate Luther’s coarse humor: “From a depressed ass, can come no happy fart.” But with or without Luther’s humor, you will need parties, song, companions and celebration. It’s the law of reformations.

Finally, this reformation headlines the prayer Veni, Creator Spiritus! “Come, Holy Spirit, renew your whole creation!” You can plan your day around that prayer.

Larry Rasmussen

[download this lecture here]