Inspired by the cap and the gown, that's on the coat hook

from GZA – Alphabets Lyrics on Rap Genius

Meaning

On a simple level he is stating that he can get inspiration from mundane random sources such as cap gowns and coat hook.

On a deeper level when GZA says “inspired by the cap and gown that’s on the coat hook” i think he’s referencing growth in knowledge, since a cap and gown represent graduation in educational institutions. So his main aim is to ascertain knowledge in order to have substantially “driven raps”. Referenced in the line before.

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