He was a merchant, and instead of writing a book actually did the thing and spread the practice: https://en.m.wikipedia.org/wiki/Double-entry_bookkeeping https

He was a merchant, and instead of writing a book actually did the thing and spread the practice: https://en.m.wikipedia.org/wiki/Double-entry_bookkeeping https://en.m.wikipedia.org/wiki/Double-entry_bookkeeping