Flat tire yesterday

Went out to the garage. Started wheeling my bike out. Found I had a flat. Curses flowed like beer at a frat party. Tried to find the puncture agent - no dice. Wasn't going to put a new tube into the tire if I can't find the thorn or wire or shank or shard of glass that rendered my tube deflated.

-sigh-

I was really looking forward to the ride yesterday.
I fixed the tube last night. Still couldn't find a cause. So we'll see if the tube stands up to the ride to work today.