Current research into the nature of dreams indicates they're not the fanciful frightening narratives that we "remember" in the morning. Instead, they're unconnected images and impressions that we only weave into a continuous tale upon waking.

It's not just dreams; this happens continuously during our waking life as well. To mangle a phrase, "The more things change, the more we see them as the same". Take the Goldberg family. Every year, on 17 June, they photograph themselves. The whole collection of photographs from 1976 to 2005 is here, but a few selections are below.

Simply judging from the images alone, these are obviously different people. While they might be similar, their facial characteristics have changed, the hair and clothes are different, and so on. Yet we perceive them as being the same persons. You do the same thing when you visit your relatives and remark on how big/small/old/young they've become. I am startled every time I see my mother and her white hair - she is not the person I am visually expecting (even though her hair turned white half a decade ago).

Descartes uses the example of a bit of honeycomb to demonstrate the same thing. He shows that though the qualities (specifically, the secondary qualities) change, we still recognize the primary quality of the item as being the same.

Our minds fill in the gaps, allowing me to recognize my mother, Descartes to play with wax, or for all of us to see the Goldberg family as they grow older. Our minds weave these impressions into a continuous seamless whole - even though they most emphatically are not. As Descartes points out, this shows that we are never directly receiving input from our senses. Instead, what we call "sensing" is really the way we think about, interpret, and even manipulate that data before it comes to our conscious attention.

My wife, studying sociology, frequently reiterates, "We create our own reality". Judging from Meditation #2, Descartes would definitely approve.