“We are nothing but what we derive from the air we breathe, the climate we inhabit,” wrote J. Hector St. John de Crèvecoeur in his Letters from an American Farmer (1782). “Those who live near the sea, feed more on fish than on flesh, and often encounter that boisterous element. This renders them more bold and compromising.”

Forty-five years ago, cosmologist Brandon Carter postulated that no observer should expect to find that he or she had come into existence exceptionally early in the history of his or her species. “Suppose you know that your name is in a lottery urn,” writes philosopher John Leslie, “but not how many other names the urn contains. You estimate, however, that there’s a half chance it contains a thousand names, and a half chance of its containing only ten. Your name then appears among the first three drawn from the urn. Don’t you have rather strong grounds for revising your estimate? Shouldn’t you now think it very improbable that there are another 997 names waiting to be drawn?”

“When summer and winter separate,” wrote Hildegard of Bingen circa 1158, “so that either summer recedes and winter arrives or winter recedes and summer arrives, then a certain mixed substance appears, flying in the air, like a whiteness of threads, where the air is purifying itself.”