What are dreams, mum?

I was a very inquisitive child, or at least so I've been told, and the beginning of my ability to speak was marked with an onset of a daily torrent of interrogations, which I subjected my mother to. I used to ask my mum -- the all knowing oracle -- about basically anything and everything.

"What are dreams, mum?" -- I inquired one day. This question, as she later told me, had stumped her at the time -- she didn't expect it coming from a six year old, any more than she knew how to explain it to one. 

"Well" -- stalled the oracle a little as she gathered her thoughts -- "they're a kind of recapitulation, night-time thoughts if you will, a replay of the experiences you had during the day -- that includes the people you may have encountered during that day, such as your friends and your teachers". 

"So if I were to encounter a monster" -- I pried (I was obsessed with dinosaurs and monsters) -- "I may dream about one the following night?"

"Yes, although as you know there really are no monsters" -- my mum took the opportunity to reassure me.

"So if dreams are night thoughts about the things I encounter during the day" -- I persisted -- "why do I sometimes dream about monsters?"

Here, my mum was a little stumped, and didn't know what else to say -- after all she didn't have a degree in psychology. After a little while she refined her answer -- she always came through, being the oracle -- "You may also dream about any thoughts that you may have during the day -- why, you may even dream about your auntie who lives in America!"

"What if I think hard enough about something I like" -- the merciless torrent continued -- "I may dream about it too?" -- I asked, brimming with excitement about having devised an idea for an experiment to be conducted over the coming days and nights.

Now, having looked back, I realize that I've never actually stopped asking such questions.