FOM: Re: Picturing categorical set theory, reply to Silver

[Vaughan Pratt]

From: Colin McLarty
>Certainly no specific picture motivates general category theory, where
>the whole idea is to have a huge range of applications.

Hopefully my previous message makes clear that this is one point where
I disagree with Colin.  The picture of a morphism as a one-dimensional
continuum along which transformation takes place is to my thinking
a suitably canonical picture of the essence of morphism.  Obviously it
isn't at the level of superrealism where you see the radiator caps on the
Mack trucks moving along these highways, or even the individual points
making up the road, the picture is more like an expressionist painting,
with just enough brush strokes to convey the essential concept.

Vaughan Pratt