Poets are commonly spoken of as psychologically unreliable; and generally there is a vague association between wreathing laurels in your hair and sticking straws in it. Facts and history utterly contradict this view. Most of the very great poets have been not only sane, but extremely businesslike; and if Shakespeare ever really held horses, it was because he was much the safest man to hold them.
Imagination does not breed insanity. Exactly what does breed insanity is reason. Poets do not go mad; but chess-players do. Mathematicians go mad, and cashiers; but creative artist very seldom. I am not, as will be seen, in any sense attacking logic: I only say that this danger does lie in logic not in imagination.
from Orthodoxy by G.K. Chesterton
