Scott Aaronson described Umeshisms: aphorisms of the form “if you never have $problem, you're spending too much effort avoiding $problem”. He asked his readers for more, but despite their computer-scienciness, no one suggested the obvious:
If your programs never have bugs, you're being too careful.
Or, from a language viewpoint:
If your language never has runtime errors, it's rejecting too many correct programs.
There's obviously a mathematical point to this aphorism schema, but it's surprisingly hard to state it explicitly. Try it: you wind up with enough conditions of continuity and monotonicity (and maybe others I missed) to completely obscure the point. That's why we use aphorisms instead.