A library may be very large; but if it is in disorder, it is not so useful as one that is small but well arranged. In the same way, you may have a great mass of knowledge, but if you have not worked it up by thinking it over for yourself, it has much less value than a far smaller amount which you have thoroughly pondered. For it is only when you look at your knowledge from all sides, and combine the things you know by comparing truth with truth, that you obtain a complete hold over your knowledge and turn it into power.
Reading and learning are things that anyone can freely do; but not so thinking. Thinking must be kindled, like a fire by a drought; it must be sustained by some interest in the matter in hand.
It is incredible what a different effect is produced upon the mind by reading, as compared with thinking for oneself: reading forces alien thoughts upon the mind—thoughts which are as foreign to the drift and temper in which it may be for the moment, as the seal is to wax on which it imprints. With reading, the mind is thus entirely under compulsion from without; it is driven to think this or that, though for the moment it may not have the slightest impulse or inclination to do so.
By thinking yourself, you follow the impulse of your own mind, which you determine by utility and purpose at the time, either by environment or recollection. The visible surrounding world does not, as reading does, impress a single definite thought upon your mind, but rather merely gives the matter and occasion which lead you to think what is appropriate to your nature and present temper. Whereas reading deprives the mind of all elasticity, like a a spring kept continually under pressure. The surest way of having no thoughts of one’s own is to take up a book every moment one has nothing else to do. This habit explains why erudition makes most people more stupid and silly than they are by nature, and prevents their writings from obtaining any measure of success. They remain, in Pope’s words: For ever reading, never to be read!
People of learning do their reading in the pages of a book. Thinkers and people of genius go straight to the book of Nature, and then enlighten the world, carrying humanity further on its way. If your thoughts are to have truth and life in them, they must be your own fundamental thoughts; for these are the only ones that you can fully and wholly understand. And reading is nothing more than a substitute for thought of one’s own.