Wade asked what the thirty or so works are that one should read to have a basic education in philosophy. Here is my list -- nothing surprising here at all. With this should go a firm command of mathematical logic.
Plato: Euthyphro, Crito, Apology, Phaedo, Gorgias, Republic, Philebus, Symposium, Sophist, Parmenides
Aristotle: Nichomchaean Ethics, Physics, Metaphysics, de Anima
St. Augustine; City of God
St. Thomas: Summa Theologica
Locke: Essay on the Human Understanding, Second Treatise of Civil Government
Berkeley: Principles of Human Knowledge
Hume: Treatise of Human Nature, Enquiry Concerning the Human Understanding, Dialogues Concerning Natural Religion
Descartes: Meditations [with the Objections and Replies], Discourse on Method
Spinoza: Ethics [extra credit: Short Treratise]
Kant: Critique of Pure Reason, Groundwork of the Metaphysics of Morals, Critique of Judgment
Rousseau: Of the Social Contract [extra credit: Emile]
That is thirty one, I think, and takes you up to 1800. At that point, all bets are off, and you are on your own.
This is a lot of stuff, but think about it. If you are a graduate student in philosophy, could you read six of these books a year? Of course you could. Some are a breeze, some will take a humongous amount of effort. But when you are done, you will have a grounding in philosophy that will last a lifetime. You can take the rest of your life to fill in all the gaps, of which there are lots.