He needed his friend and math genius, Marcel Grossman, to turn his imagination into a workable theory. AI may be our own personal Marcel Grossman at this point.

Here is his quote:

"Imagination is more important than knowledge. For knowledge is limited, whereas imagination encircles the world,” means that facts alone only describe what currently exists, while imagination allows us to discover what is yet unproven or unbuilt"

This probably sums up the current AI limitation nicely.