Sir William Petty wrote at length on issues that would later concern economists, such as taxation, Velocity of money and national income, but while his analysis was numerical, he rejected abstract mathematical methodology.
Sir William Petty menulis panjang lebar tentang isu-isu yang nantinya akan menjadi perhatian para ekonom, seperti perpajakan, Perputaran uang dan pendapatan nasional, tapi sementara itu analisis numerik, ia menolak abstrak matematika metodologi.