Thomas Mun was a director of the East India Company and the most lucid English statement of the mercantile system, which he was defending rather than describing.
The Company was under attack for exporting silver to Asia, which on the crude bullionist view was a direct drain on national wealth. Mun's answer, in England's Treasure by Forraign Trade — written in the 1620s, published by his son in 1664 — was that the objection mistook a stage for the whole. Silver sent east buys spices and calicoes; some are consumed at home and some re-exported to Europe at a profit; what returns exceeds what left. The right measure is therefore not any single transaction but the balance of the kingdom's whole trade over a year: "sell more to strangers yearly than wee consume of theirs in value."
That formulation is the mercantile system's clearest self-description, and it contains the assumptions that made it a target. Wealth is a stock of treasure rather than a flow of goods; trade is a contest in which the surplus one country gains another must lose; and the state is therefore justified in shaping commerce by tariff, monopoly grant and navigation law. Mun also drew the conclusions employers usually draw from it, arguing against domestic consumption and for wages low enough to keep exports competitive.
Smith read him closely and attacked him by name, and the modern balance-of-payments account descends from his framing even where the policy conclusions have been abandoned. The mercantile argument has never really gone away: every case for industrial policy and managed trade restates some part of it.