I don’t know much about Pliny, but Pliny’s treatment of Eratosthenes, which just precedes the section you quoted, indicates Pliny does understand the math. Pliny writes of it that:
it is supported by such subtle arguments that we cannot refuse our assent
Doesn’t that indicate that Pliny had read and followed Eratosthenes’ argument?
Pliny’s later digression on a story about a letter seems irrelevant to this issue. The story doesn’t look to be a substitution for a mathematical case; it looks like it’s supposed to be only an anecdote.
I don’t know much about Pliny, but Pliny’s treatment of Eratosthenes, which just precedes the section you quoted, indicates Pliny does understand the math. Pliny writes of it that:
Doesn’t that indicate that Pliny had read and followed Eratosthenes’ argument?
Pliny’s later digression on a story about a letter seems irrelevant to this issue. The story doesn’t look to be a substitution for a mathematical case; it looks like it’s supposed to be only an anecdote.
Yes, Pliny asserts that he followed Eratosthenes’s argument. I don’t believe him.
I do believe that he has read an account of the argument, traces of which are in 2.75 (and 76 mentions Eratosthenes by name).
Fair enough.