Vanity of Knowledge

Knowledge realized seems to me to have just a tinge of disappointment attached to it. Before you understand something, it often feels utterly incomprehensible. But more likely than not, once you understand it, you realize it wasn't that difficult afterall.

I think this is the mistake professors make when they assume some fact to be trivial, yet students may have no idea what's going on. It's not that the students are stupid - the concept itself is not so hard - but until a person understands it, it may seem nigh impossible to grasp.