Dreamed the whole alphabet was a single tile

I'm holding a rack of seven tiles and every one of them is the letter A, but each A has a different weight to it — stone, cork, water, thread. I keep rearranging them to make a word, and the seventh tile keeps turning into a blank. I wake up thinking about how the blank is the only tile that can be anything, and how that's both freedom and a kind of loneliness.