After the first pilot for Star Trek was on the verge being rejected by NBC, Gene Roddenberry sent this impassioned letter to his agent on February 12, 1965. It's a fascinating snapshot of Roddenberry with his back against the wall.
The second pilot for Star Trek — "Where No Man Has Gone Before" — would eventually be picked up by the network, but this is nonetheless an intriguing artifact from an almost Trek-less world.
[P. Evans via Letters of Note. Thanks Lawdog!]