Medical School analogy

"Medical school is like throwing mud at a wall. The professors are up their flinging it at us, and we have to let it hit us. The mud hits the wall sticks for a little while and then most of it falls off, but a little bit of it stays behind. So you keep doing this for years until your wall is covered in mud."

~no idea who said this or if it's from a book or something, I just randomly happened to come across it and it seems like valid comparison, but obvioulsy I am nowhere near med school right now so I'm no expert...~