No, it’s not about drugs. Get over it.
It’s about… wait for it… mathematics.
Just let that sink in for a moment.
Okay, well, perhaps that was a bit misleading; the idea that Alice’s Adventures in Wonderland is a mathematical allegory is only one of many theories surrounding the book. The leading theory is that the book represents personal growth, and the hallucinogen theory is considered complete rubbish by most experts. However, neither of the more popular theories account for the numerous depictions of geometric properties.
Plus, the author was a mathematician.
I think this theory makes the books at least twice as good :)