I like how in old animation, you knew what object the characters would interact with. Because they were significantly less detailed than the stationary objects around them.
That’s because stationary objects and backgrounds are normally painted or drawn first, and the things that will require animation are painted onto clear plastic sheets of paper that lay above the background. That way, the animators don’t have to redraw the background for every frame.
(Source: , via loveisreckless)