Brother Luca Pacioli's accounting methods worked for centuries before he documented them as 37 chapters of his textbook Summa de arithmetica, geometria. Proportioni et proportionalita, published 1494 in Venice, illustrated with etchings of Leonardo's. Although he didn't invent the accounting method, he is regarded as 'The Father of Accounting', and these chapters are the earliest known text about double-entry book keeping.
The accounting method he details has been known as 'The Method of Venice', 'Italian Accounting', and 'The System of Debits and Credits'. These days it's known as 'Double Entry Book Keeping', or 'GAAP'.
A quote from Pacioli's times:
There is nothing more difficult to take in hand, more perilous to conduct, or more uncertain in its success, than to take the lead in the introduction of a new system. The leader will have for his enemies all those who are well off under the existing system, and only lukewarm supporters in those who might be better off under the new. Machiavelli, about Fra Luca's System