Exactly. I have so much pity for those tasked with defining terms and applying hard and fast dates to movements. It's really a never ending and ultimately impossible task, as there is in fact no line between an "event" and its causes. Add to that the fact that the history of ideas is constantly circling back on itself, rediscovering threads from long ago movements which had been put down over time in favor of others, and you have a case where the same things (more or less) are being given a series of different names. Then again, language is constantly working to create the appearance of separation and distinction where in fact there is only continuum. But without false separation, it's hard to tell somebody how to get to the Chisos Basin, for example, or how to make an omelette. Function, it seems, comes at the cost of simplification, and therefore, inaccuracy.

At times like this, a certain modest mouse quote comes to mind: "language is the liquid that we're all dissolved in, great for solving problems after it creates the problems."