It's rather strange (and disheartening, really) that his name hasn't achieved the level of popular recognition that Plato, Aristotle, Descartes and Kant have received, but maybe that has something to do with the fact that his ideas challenged many notions that most of us consider sacred (and I'm talking about concepts like causality, induction, substance, and the self... I won't even get started with religious notions, which are really child's play).
Here is just one example of his incredibly sharp thinking (from his Enquiry Concerning Human Understanding): in this quote (known as Hume's fork), he summarizes the insight that any alleged piece of knowledge must be able to satisfy one of two basic conditions in order to deserve to be listened to:
When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: For it can contain nothing but sophistry and illusion.Good-bye religion!
And in this one (from his Treatise of Human Nature), he argues that reason cannot work as a cause of action:
A passion is an original existence, or, if you will, modification of existence, and contains not any representative quality, which renders it a copy of any other existence or modification. When I am angry, I am actually possest with the passion, and in that emotion have no more a reference to any other object, than when I am thirsty, or sick, or more than five foot high. It is impossible, therefore, that this passion can be opposed by, or be contradictory to truth and reason; since this contradiction consists in the disagreement of ideas, considered as copies, with those objects, which they represent.Good-bye morality as a rational enterprise :)
Cheers to you, bon David!