David Letterman had already experimented with an earlier version of his show, as well as several appearances as substitute host on 'The Tonight Show,' when the chance to do a full-time late night program came around. Instead of replacing the emcee of 'Tonight,' he would get his own playing ground.
And what a time it would be.
Letterman's humor was both more cerebral and exponentially more adventurous than that of his competitors. He quizzed the audience members about random pictures, talked people into doing bizarre pranks in the middle of a crowded Manhattan street, invited folks to have their pets do crazy stunts on stage and walked outside just to see what was going on.
If anything could be done in a normal, routine way... David would do an end run around it.
He is on another network today, but the recipe was as good at the beginning as it is now.
Funny and brilliant-- there *is* television for which it's worth it to stay up late.