“Learning never exhausts the mind.”

“Learning is the only thing the mind never exhausts, never fears, and never regrets.”

“The best thing for being sad," replied Merlin, beginning to puff and blow, "is to learn something. That's the only thing that never fails. You may grow old and trembling in your anatomies, you may lie awake at night listening to the disorder of your veins, you may miss your only love, you may see the world about you devastated by evil lunatics, or know your honour trampled in the sewers of baser minds. There is only one thing for it then — to learn. Learn why the world wags and what wags it. That is the only thing which the mind can never exhaust, never alienate, never be tortured by, never fear or distrust, and never dream of regretting. Learning is the only thing for you. Look what a lot of things there are to learn.”

“When the mind is exhausted of images, it invents its own.”

“The problem with any philosophical consideration is that once you open a door in your mind, you can never close it. Once you learn something, you can never convince your mind that you didn't learn it. If you learn the world is round, you can never fit in with a world that thinks it's flat.”

“Before forty, you think that exhaustion is something like a long-lasting hangover. But at forty you learn all about it. Even your passions exhaust you.”