Willis’s primary interest was shorthand writing—he is chiefly noted forArt of Stenographie—andhis memory treatise is clearly influenced by shorthand’s mechanism of one-to-one correspondence.
John Willis's Mnemonica (Latin 1618, English 1621, 1654, and 1661) covers memory, but he was apparently more interested in shorthand writing and also wrote Art of Stenographie.
I'll have to read this for a view into the overlap of memory and shorthand with respect to the development of the major system. Did this influence others in the chain of history? It definitely fits into the right timeline.