Merlin is spot on

Merlin to Wart:

The best thing for being sad, is to learn something. Which is why I'm sharing one of my fav links with you, people.
Go look, go look.

http://www.aldaily.com/

Yup, learning something new really is the best cure for melancholy I know.

The rest of the quote:

That is 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—pure science, the only purity there is. You can learn astronomy in a lifetime, natural history in three, literature in six. And then, after you have exhausted a million lifetimes in biology and medicine and theocriticism and geography and history and economics—why, then you can start to make a cartwheel out of the appropriate wood, or spend fifty years learning to begin to learn to beat your adversary at fencing.
After that you can start on mathematics, until it is time to learn to plough.

T.H. White in The Once and Future King