Jim Holt is an elegant and entertaining writer on all things mathematical and scientific.  Let me supply some quotes from an essay he wrote in The New York Review on the four color theorem.  (Unfortunately, the online article is available only to archive subscribers):

Mathematicians, it should be noted, were slow to warm to computers. Traditionally, from Pythagoras on, they have relied on pure hard thought to gain knowledge of new truths. It used to be said that a mathematics department was the second cheapest for a university to fund, because its members required only pencils, paper, and wastebaskets. (The cheapest would be the philosophers, because they don't need the wastebaskets.) As late as 1986, a mathematician at Stanford boasted that his department had fewer computers than any other, including French literature

[....]

The four-color breakthrough marked a shift in mathematical practice. Since then, several other conjectures have been resolved with the aid of computers (notably, in 1988, the nonexistence of a projective plane of order ten). Meanwhile, mathematicians have tidied up the Haken-Appel argument so that the computer part is much shorter, and some still hope that a traditional, elegant, and illuminating proof of the four-color theorem will someday be found. It was the desire for illumination, after all, that motivated so many to work on the problem, even to devote their lives to it, during its long history. (One mathematician had his bride color maps on their honeymoon.)