We forget what we say or write most of the time. Ask me about the notes I took in class today, I might not be able to recite everything to you without referring. Same with blogs and assignments. I just received my essays from last semester and when I read it, all that went through my mind was, "Did I write that?" "That was a dumb mistake!! Why did I do that!" and similar thoughts.
Refer to a random post you made a few months ago and you'll see what I mean.