He is known for authoring around 15 pamphlets on various economic and financial topics, contributing to the development of political economy before the seminal works of Adam Smith.
The catalogue of his collection, dated 1764, is preserved as Lansdowne MS. 1049 in the British Museum and provides valuable insights into economic bibliography.
He devoted much of his time to compiling detailed statistics, which challenged contemporary fears of a decline in British trade.
Massie addressed topics such as urbanization, commerce, and public finance, with a particular focus on the problem of government debt during the Seven Years' War.
His contributions to economic thought, while sometimes overlooked, remain significant for their effort to blend historical knowledge with contemporary analysis.