It's all been done before!

What do you know was browsing the web and came across a lesson plan for "recycled poetry" http://www.imakenews.com/eletra/mod_print_view.cfm?this_id=101058&u=psla
It's very hard these days to have an original idea. Whatever you think of if you look hard enough you will find that it's been done before. Does this make your idea less valid though? If you came up with it by yourself following your own explorations and ideas. It has often been the case that people in different parts of the world have come up with the same original idea at around the same time. Is this because of a collective consciousness? or is it that when an idea is ready to be born it is born of many minds at the same time? It's an interesting question, sceptics might say that there are no original ideas left and that everything (music, art, writing) has all been done before - I don't know the answer, but I do know that I'm going to keep following my ideas whether they turn ot to be original or not.