WEEK THREE - BONUS QUESTION

As we find ourselves in Virginia at the site of a Civil War battle (or maybe just the reenactment thereof), here's a related question!

The following describes what man, and what is his greatest contribution to the world (two hints: he's a hero of mine, and Webster probably saw him as competition)?

This Yale-trained doctor volunteered his medical services as a captain during the Civil War, and subsequently went bat-shit crazy. He finally got so paranoid that he killed a man who he thought was after him, and got sent to insane asylums. He started collecting rare books, which proved invaluable to his future "profession".

Good luck!

And one more clue just to confuse you more: gangsta d'oh!