There are many different theories, I will list a few. It seems like no one will ever really know 1.. Dreams are a result of you subconscious thoughts and desires. 2.. It is associated with what you know, and is just like thinking but it adds a visual image.3.. The subconscious mind trying to communicate to us that the conscious mind tries to ignore.
But there must be many other reasons, like why we have nightmares... etc. I really do not think it will ever be know why we have dreams. The brain is very complexed and much is not known about it. Sorry it has taken so long for someone to answer your question.
I really hope this helps.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.