I would probably guess that he believed in an eventual theory of general intelligence/consciousness, but probably not that it will be easy/succinct/simple. For example, Neural Networks have made extreme breakthroughs in sensory perception and classification, partly through modeling how humans perceive and classify. But do those theories extend over to other areas of intelligence like Planning? Creative capabilities? Emotion? Empathy? Especially if we know that there are other players (such as hormones, genetics, epigenetics, culture, etc.) beyond Neurons in those areas? The fact of the matter is that there are countless factors in how intelligence develops, let alone influence the development of all of the auxiliary functions for intelligence (such as memory, reflexes, sensory, etc.).
EDIT: You can get a little intro to his thoughts on the matter starting about 27:16 in this video [1] (linked at the time marker). If you watch for about 10 minutes, he demonstrates some of the difficulties of using single abstractions for something as complex as human intelligence.
EDIT: You can get a little intro to his thoughts on the matter starting about 27:16 in this video [1] (linked at the time marker). If you watch for about 10 minutes, he demonstrates some of the difficulties of using single abstractions for something as complex as human intelligence.
[1] https://youtu.be/-pb3z2w9gDg?t=1636