Expressible conscious thought is limited to just a bit beyond what is readily typed or spoken. Not all thought is conscious. Just about every take-home test in grad school, I'd wrestle with the problem, go to bed thinking I was going to flunk, then find myself writing down the answers over breakfast.
There's the "tip of the tongue" experience, where you know you should be able to know something, but can't quite get it out. This not only happens with memory. It also happens with problem solving. This tells me that there's also unconscious thought and inexpressible thought we are conscious of.