James Brydges, 1st Duke of Chandos in the context of Duke of Chandos

Duke is a male title either of a monarch ruling over a duchy, or of a member of royalty, or nobility. As rulers, dukes are ranked below emperors, kings, grand princes, grand dukes, and above sovereign princes. As royalty or nobility, they are ranked below grand dukes and above or below princes, depending on the country or specific title. The title comes from French duc, itself from the Latin dux, 'leader', a term used in republican Rome to refer to a military commander without an official rank (particularly one of Germanic or Celtic origin), and later coming to mean the leading military commander of a province. In most countries, the word duchess is the female equivalent.

Following the reforms of the emperor Diocletian (which separated the civilian and military administrations of the Roman provinces), a dux became the military commander in each province. The title dux, Hellenised to doux, survived in the Eastern Roman Empire where it continued in several contexts, signifying a rank equivalent to a captain or general. Later on, in the 11th century, the title Megas Doux was introduced for the post of commander-in-chief of the entire navy.

Richard Cantillon (French: [kɑ̃tijɔ̃]; 1680s – May 1734) was an Irish-French economist and author of Essai Sur La Nature Du Commerce En Général (Essay on the Nature of Trade in General), a book considered by William Stanley Jevons to be the "cradle of political economy". Although little information exists on Cantillon's life, it is known that he became a successful banker and merchant at an early age. His success was largely derived from the political and business connections he made through his family and through an early employer, James Brydges. During the late 1710s and early 1720s, Cantillon speculated in, and later helped fund, John Law's Mississippi Company, from which he acquired great wealth. However, his success came at a cost to his debtors, who pursued him with lawsuits, criminal charges, and even murder plots until his death in 1734.

Essai remains Cantillon's only surviving contribution to economics. It was written around 1730 and circulated widely in manuscript form, but was not published until 1755. His work was translated into Spanish by Gaspar Melchor de Jovellanos, probably in the late 1770s, and considered essential reading for political economy. Despite having much influence on the early development of the physiocrat and classical schools of thought, Essai was largely forgotten until its rediscovery by Jevons in the late 19th century. Cantillon was influenced by his experiences as a banker, and especially by the speculative bubble of John Law's Mississippi Company. He was also heavily influenced by prior economists, especially William Petty.