Certain things have a reliance upon other things for their existence. The Cheshire cat is a philosophical joke as it leaves a mouth, without a face or head. Thusly disproving the philosophy (of course, he's not real, so he disproves nothing)
There are lots of subtleties to Alice in Wonderland. Other than the blatant drug hints. There's more philosophy stuff to it as well, but I have forgotten. Timeless books