The greater part of mankind may be divided into two classes; that of shallow thinkers, who fall short of the truth; and that of abstruse thinkers, who go beyond it. The latter class are by far the most rare: and I may add, by far the most useful and valuable. They suggest hints, at least, and start difficulties, which they want, perhaps, skill to pursue; but which may produce fine discoveries, when handled by men who have a more just way of thinking. At worst, what they say is uncommon; and if it should cost some pains to comprehend it, one has, however, the pleasure of hearing something that is new. An author is little to be valued, who tells us nothing but what we can learn from every coffee-house conversation.

David Hume, "Of Commerce"

General Philosophy Resources

Peter Suber's Guide to Philosophy on the Internet

Philosophical Dictionary

The Internet Encyclopedia of Philosophy