Google Sapir-Whorf and check out some of the college/university websites that show up - you should get a decent discussion that way... The hypothesis is essentially that language guides our thinking - provides us with ways of viewing the world - and so, in a sense, "creates" or "dictates" our reality. An alternative name for Sapir-Whorf is "linguistic relativitism". The opposite view is that language merely reflects our reality... I've oversimplified this... er, A LOT!