Plato & Sigmond Freud

Plato

Our senses give us a very effective perception of the world and are our only means of grasping anything that happens around us... If anything is actually happening at all. It could be that we are all in the matrix and our senses are all being deceived, but most likely not. Our senses are sometimes unreliable but not very much. Optical illusions trick our eyes and hallucinations can fabricate things that aren't even there but mostly our senses will be correct most of the time. Two peoples entire perception of the world could be different, however. As long as peoples' senses are different enough their realities would be different; one person's orange may be red, another may have pink for green, and some could have no color at all.

Our materialism is in part because of our senses. A blind man can sit in any house, big or small, and as long as he was comfortable wouldn't care about the size or condition of the house because he wouldn't be materialistic. A lack of senses would probably produce closer bonds to living things than anything material. Since senses are our only means of having a reality whatsoever it is to me impossible to fathom anything but a sensory world, just as it is impossible to conjure a new color or smell in the mind.

Freud

Dreams, in my opinion, have no specific use to people. Dreams can have emotional usefulness like reuniting a person with a loved one or creating an interesting story but to say they have a specific purpose like to advise or guide you doesn't seem realistic. Your mind can create the most intriguing and/or horrifying dreams like being chased by someone or gaining supernatural powers. I have very few dreams that I ever remember but one in particular involves me exploring the jungle with a group of people. The only horrifying dream I remember are the ones where you fall of a cliff. Most people forget their dreams because they aren't important. They are usually very random and with everything people do during the day if just doesn't matter. Of course the answer is probably more scientific than just saying that it's unimportant and we're busy but we'll have to wait for science to advance enough to answer the question. Dreaming is a purely mental activity and occurs in REM sleep stages of your sleep. There is heightened mental activity during those stages as well.