In honor of Hip Hop's 50th birthday, Tracklib pulled together an incredible video breaking down the iconic samples of every year from 1973-2003.
My personal favorite is how J Dilla flipped "I Can't Stand (To See You Cry)" by The Escorts (1974) into Don't Cry (as featured on his too-good album Donuts).
The whole video is worth 30 minutes of your time.