I saw some friends today; one of them I know well: she cuts my hair.
The other woman I had met in the barber's shop - I couldn't remember her name. She told me, and then said, "You were telling us a story about a bird."
"Probably a crow," I said.
"Yes, that's it!" she said, "and it was about a crow inventing… something…"
"Geometry?" I asked.

As a gardener, I'm fond of the saying, there are no straight lines in nature.
It's certainly true, and applies to landscapes.
I have a garden with raised beds (old-growth cedar and douglas fir) - the lines are straight, the paths are straight, the boxes are parallel and perpendicular - precisely - and they are fucking level as hell.
If I am going to impose straight lines upon nature, they had better be straight.

Nature, however, and as we're reminded, doesn't have straight lines. Think about it: it's true, as you soon realize. Sure, there are conifers that grow straight (since they grow away from gravity, rather than toward light), but they're a mere approximation of linear - a good one, but there's some flex going on there.
So there are no straight lines.

And yet - how do we express straight lines, as between landmarks?
"As the crow flies."
Say it's seventeen miles from my house to the Meerkerk Rhododendron Garden, but it's only nine miles, as the crow flies.

As I was telling my friends today, while recapping the story for the benefit of one or two others who weren't there that day in the barber shop, no doubt the Greeks had an example of this very phenomenon - I am sure of it. For example, the well-known story by Mark Twain, The Jumping Frog of Calaveras County, was preceded by some two thousand years or so, in a virtually-identical story from Greek lore.
Twain himself pointed out the similarity down to the last details: in his story, the frog, weighted down with pebbles, "Heisted and heisted himself, but it warn't no use. He couldn't budge." In the Greek version, the frog tried to jump, but couldn't, and tried again…
"So, you see," Twain said then, "there's nothing new under the sun."

If the Greeks could have such a capable example of a folk-tale, as spun by one of the nineteenth century masters, then no doubt they would have had as simple a bon mot as ours for "As the crow flies." [although I routinely promise, I really will look into it.]

Having led this far, it's easy for me to maintain that crows were the early exemplars of straight lines to the Greeks. No doubt, as Newton glimpsed the principle of gravity while watching the moon when an apple fell, some early philosopher noted the linear flight of a crow, among flocks of starlings or others, and recognized the special, unique phenomenon of a line.
Perhaps this was Euclid himself.
Or - perhaps Euclid himself
was a crow.