I realized that they were deep ideas (in the sense of hidden in remote places of my mind, not even visible to me) when I realized that some drawings I had made were very similar to a frieze of a public building in my city. The unusual thing was that I had never noticed that frieze, or not consciously at least. One day I noticed it as I walked by it. I found that frieze incredibly familiar, and then I realized why. The drawing - which is a largely unconscious activity - had conjured it up from a room of my memory.
So I can say that drawing is also memory, though not conscious. By drawing I don't explicitly recall a memory but only later I realize that it is similar to something I had seen years ago. Sometimes people who look at my paintings tell me that they remember the work of this painter or that painter. Needless to say, while I was creating them I wasn't thinking about it at all, yet I recognize common elements in them.
For me, painting is a form of research without an aim: I don't know what I'm looking for but I know that, when I find something, it was already inside me. I just haven't seen it yet.