Running Commentary 9/8/2025

Hello,

The first waves of Fall migrants are passing through Michigan. I found a half-dozen yellowlegs in a runoff pond near a Wal-Mart this evening. I think they’re greater yellowlegs based on their bill length and the fact that they seemed big for sandpipers compared to a convenient nearby reference mallard, but they were quiet so I’m not certain. Here’s a photo if you want to take a crack at IDing them yourself:

Anyway...

Reading...

I got this book from my library as an audiobook, which is an odd way to experience a book largely about geometric diagrams. But I think even with a hard copy this would be an odd read. It’s a relatively short commentary about Euclid’s Elements that comes off like an enthusiastic fan tribute to the millennia-old mathematics text. Here are my notes:

• The book is subtitled "Euclid and His Elements" but Berlinski is quick to acknowledge that almost nothing is known of Euclid except that he wrote The Elements. This book is thus not at all a biography of Euclid but instead a commentary and history of The Elements.
• Berlinski's commentary on Euclid's Elements focuses mainly on Euclid's logic of axioms and theorems, which became foundational not just to geometry but to mathematics overall. He examines how Euclid's approach to teaching has carried his work into the modern day. Even as mathematicians have improved on his methods or challenged his conclusions in certain instances, they have not superseded The Elements as a whole—particularly not in its aesthetic value.
• Much of the end of the book deals with Euclid's Parallel Postulate, something he offered relatively tentatively and which many mathematicians since Euclid have tried to either prove logically or to dismiss as unfounded. Today this postulate—the defining characteristic of Euclidean geometry, wherein the plane is conventionally flat—is not upheld in elliptic and hyperbolic geometries, even though his first four postulates still do.
• If Euclid's Elements are an expression of his deep love of geometry, then this book, in turn, is an expression of Berlinski's love of Euclid's work. This is not a crucial work for a mathematician to read, but I'm glad to have found Berlinski's work anyway.

Bird of the Week

This week we have a bird I always like to see. It’s not an especially pretty bird, nor is it an exciting rarity or migrant. But it’s a bird that, when I do see it, it makes me happy, both because it’s a charming little creature and because it’s a fortunate thing to see a Brown Creeper.

This bird is the only one of its kind found in North America. There are a mere nine members of the treecreeper family in the world, with the other eight found in Eurasia — especially in the forested foothills of the Himalayas, to which three species are endemic and a fourth is also found. All nine are brown, for what it's worth, and for an obvious reason given their habits. Treecreepers are not creepy — as I said, they’re fairly charming, looking like slim little wrens — but are, rather, creeping. They feed on insects found on tree bark as they slowly, windingly ascend the sides of tree trunks and large limbs. They never creep downwards, as nuthatches and certain other clinging birds will; when they’ve gotten sufficiently high up in their climb, they’ll drop off, flying either back to the start or to another nearby starting place. An inattentive person won’t notice that there is a bird there, as it behaves almost like a falling leaf when it descends. Every time I’ve seen one there’s been a sudden realization, “Oh, that’s a creeper!” That thrill of sudden spotting and identification is one of the key joys of birding, and it’s a consistent thing when it comes to creepers. You can’t count on seeing one, you can’t really go looking for them, you just have to be out in the woods and attentive and hope you come across one. I last found one at the end of August, climbing up a tree where a warbling vireo was singing; if I hadn’t been looking for the vireo, I wouldn’t have seen it.

Creepers are sneaky, but they aren’t silent. They have a nice little song of quick, very high notes, or else they’ll give soft little two-note calls. They aren’t very loud for songbirds, but they do sing.

To science the brown creeper is Certhia americana, which roughly means “American treecreeper”;¹ it was first formally distinguished from the Eurasian treecreeper by C. L. Bonaparte in an 1838 comparative list of European and American birds.² Certhia is the only genus in the family Certhiidae, and its name comes from the writings of Aristotle, who referred to a bird that, at the least, matched the description of a treecreeper by the name karthios.¹