We've got some pages here that might help you with Descartes, in case he is an 'issue' for you!

One page is here.[off-stick link] It comes from a set of pages [off-stick link] which we use in connection with 2nd year modules - but we have tried to make them clear for everyone...

If you have a question, philosophical or otherwise, you could try Skyping us - me, actually. Skypename: Rumplechadwick.