But the sun is eclipsed by the moon.

Recognize those lines? Yes, it’s from “Eclipse” by The Pink Floyd, the final track on Dark Side of the Moon. It also happens to be the epigram I chose for my dissertation on metaphysical method.

Eclipses have played a significant role in human history, mostly because of their power to scare the shit out of us. Consider the many peoples on this little planet who experienced the eclipse as a harbinger of The End, as signs of the wrath of some divine being or other, or as the unraveling of the fabric of nature.

The Maya, known for their calendar (and heart sacrifice) should be better known for their mathematics. The Dresden Codex, for instance, gives us a glimpse of what they could do with their understanding of math plus careful observation: They accurately predicted the occurrence of solar eclipses, and even built temples ahead of eclipses, to get a better view. The Temple of Kukulkan at Xochimilco is an example: And on the side of that beautiful temple, if you look carefully, you’ll see a glyph for “eclipse”: A mouth in the act of swallowing the disk of the sun. Which was not a cause for celebration, but a sign of angry gods.

That’s a glimpse into their fascinating worldview, in two ways. Their mathematical system is vigesimal, roughly meaning, base 20 — just the number of digits of the average human being. And the wrath of the gods was apparently regular enough to be amenable to prediction by means of mathematics. Which just goes to show that the history of our species is the story of the feeble attempt by the cerebral cortex to get a grip on the limbic system.

I took this photo of the glyph in 1991, during one of many long sojourns in Mexico in the 1980s and 1990s. This was a particularly memorable trip: I was in Mexico for one of the most spectacular eclipses of modern times, on 11 July. I was in the path of totality for 7 minutes, a profoundly creepy experience that one just cannot forget. That was when it occurred to me that the image of the eclipse might well be the best comment I could make about a book on metaphysical method.

The eclipse is sometimes cast as a beginning, too. At the “dawn” of Western philosophy, Thales, one of the Big Three Ionian cosmologists, is said to have predicted an eclipse, possibly based on knowledge of Babylonian astronomical tables. In the folklore of philosophy, we call the date of Thales’s eclipse the “birthday of philosophy” — May 28, 585 BCE — not because he predicted it, but because of what he said about predicting it. After the eclipse, people came to him to honor him as favored by the gods. According to the story, instead of allowing himself to be promoted to “divinely favored,” he responded that it wasn’t special revelation from the gods. On the contrary, he maintained that he’d worked it out, by himself, using human reason — and offered to show other people how to work it out for themselves. Another tiny bright spot in our human story.

According to my idiosyncratic take on this story, May 28, 585 BCE was not the birthday of philosophy, primarily because I believe philosophy was born with our species (if not before). On the contrary, in my view, May 28, 585 BCE was the date that philosophy and religion finalized their divorce.

Be that as it may, the eclipse still holds a mysterious, primal power over us — and it’s not just mythical. By the end of the day today, I will have witnessed two total eclipses without trying, and if I were choosing an epigram for today, it would be this line from Lucretius’s De Rerum Natura 4.325. This is the Latin and my translation, specially rendered for relevance — and informed by the human story.

Sol etiam caecat, contra si tendere pergas.
“And also, the sun will blind you, if you persist in gawking at it.”