Confused, the points you raised might look obvious but are very important in the study of dream. Good job. Indeed, we cannot dream of something beyond our intellect reach. That means dreams are manipulation of memories with or without logical sequence. As far as Descrates is concerned, I might disagree. According to him, a blind person might be dreaming all the time. Besides, scientific experiments have proven the part of the brain used during dream act differently that during normal course. There is a solid line between dreaming and living it up.