Simply speaking, Consciousness is the study about the relation between our mind and our body. Sometimes, we physically situated at somewhere but our minds go to somewhere eles... A PolyU professor shared about Consciousness in barcamphk 2010!
One key point to understand why we do something is to differentiate the following four:
For example, we went to the student canteen of PolyU for lunch yesterday... Why?
From my point of view, we need to lunch and that's our need but we can lunch anywhere instead of the student canteen. So, this is not caused by need. Is it joyful? Yup, pretty joyful when chatting with other barcampers... but we can chat anywhere. Is it the desire? or is it fear? Desire to have free lunch? or fear of paying for a lunch? em... 50/50 in this case :P but I think it should be my desire of free lunch :P