What was your PhD experience like?

I went into it thinking it was going to be all about cleverness and coming up with a clever answer, which seemed to be what undergraduate degrees are about. I think what I'd discovered from it was that it's a lot more about slogging through the books and doing the research and sticking it out. This is fine and I did, there were the clever ideas as well, but it was a lot more in-depth digging to bring them out.