Avarice, the spur of industry.

The phrase treats avarice (greed, love of gain) not primarily as a private vice but as a social motive that can drive economic activity. Calling it “the spur of industry” frames acquisitiveness as an incentive: the desire to accumulate wealth pushes people to work, innovate, trade, and increase productivity. In Humean terms, it aligns with his broader interest in how passions and self-interest, when channeled through institutions and commerce, can yield public benefits (greater “industry,” refinement, and prosperity) even if the underlying motive is morally suspect. The epigram thus captures an Enlightenment tension between moral evaluation of motives and pragmatic assessment of their effects in commercial society.