## Posts Tagged ‘**euclid**’

## Euclid’s fifth postulate

Donal O’Shea, in *The Poincare Conjecture*, quotes Farkas Bolyai’s response to his son Janos upon hearing that Janos was working on trying to prove Euclid’s fifth postulate:

I implore you to make no attempt to master the theory of parallels; you will spend all your time on it. . . . Do not try . . . either by the means you mentioned or any other means. . . . I passed all through the cheerless blackness of this night and buried in it every ray of light, every joy in life. For God’s sake, I beseech you, give it up. Fear it no less than sensual passions, because it too may take all your time, deprive you of health, peace of mind and happiness in life.

(Of course, we know that Janos Bolyai ignored his father’s advice and thus discovered non-Euclidean geometry.)

## Pure v. applied mathematics

A curious remark from Peter Green’s *The Hellenistic Age*:

Euclid and Archimedes regarded the application of theory to practical or, worse, profitable ends with withering contempt and would have nothing to do with it: it took the Roman siege of Syracuse in 212 to make Archimedes turn his mind to the problem of defense artillery.