Maybe he was saying that humans tend towards emotions and imprecise thoughts, and we must squash that tendency to become good programmers.

On the other hand, I think (although I don't have references to back it up) many people believe that humans' capacity for "algorithmic thought" is a key separation from the rest of the animal kingdom. Under that belief system, programming must be a natural act because it comes from of one of the very traits that makes us human.

We could therefore read Perlis's epigram as a rejection of that belief. But it seems odd to make a sweeping, controversial(?) statement about human nature in such a roundabout way. Is there another interpretation?

[1] http://www.cs.yale.edu/homes/perlis-alan/quotes.html