"Just buying a book" is not a way for anyone to learn anything serious. There is a negligible fraction of actual autodidacts in this world, and they are not even usually the best and the brightest -- just a weird curiosity.
Go pick up a graduate mathematics textbook (or even an undergraduate one, I'll be generous) of your choice and try to learn from it without help from an instructor. I'll wait. Best case scenario, you will believe you understand it until you come into contact with someone who actually does and be horribly embarrassed. Or perhaps so self-satisfied with your ability to surpass everyone in the universe at understanding mathematics quickly and without help or discussion that you won't be able to even grasp the fact that you don't understand it. I've seen both first hand.
English and Philosophy (especially Philosophy) are exactly the same. You cannot learn philosophy from only reading textbooks. It's where you start, not where you finish. It's the bare minimum. It's what you should have done before you even show up to the class, at which point you begin learning nearly everything there is to learn about the subject.
Almost everyone learns a GREAT deal in college. Some people do learn so little they aren't even capable of understanding what it is they were /supposed/ to learn, and post on tech message boards about how college is a waste of time.
Go pick up a graduate mathematics textbook (or even an undergraduate one, I'll be generous) of your choice and try to learn from it without help from an instructor. I'll wait. Best case scenario, you will believe you understand it until you come into contact with someone who actually does and be horribly embarrassed. Or perhaps so self-satisfied with your ability to surpass everyone in the universe at understanding mathematics quickly and without help or discussion that you won't be able to even grasp the fact that you don't understand it. I've seen both first hand.
English and Philosophy (especially Philosophy) are exactly the same. You cannot learn philosophy from only reading textbooks. It's where you start, not where you finish. It's the bare minimum. It's what you should have done before you even show up to the class, at which point you begin learning nearly everything there is to learn about the subject.
Almost everyone learns a GREAT deal in college. Some people do learn so little they aren't even capable of understanding what it is they were /supposed/ to learn, and post on tech message boards about how college is a waste of time.