The above shows the contribution Petty made to theoretical issues that have dominated the later subject of economics ever since. He covered such a wide range of topics according to his political arithmetic method, i.e. like modern economists, he set out to prove his claims by finding data and statistics, rather than relying on anecdotal evidence. He wrote rigorously, but also with concision and humour. The issues that Petty thought about and wrote are major topics that have plagued the minds of economic theorists ever since.