Hume’s distinction between the calm and violent passions is one whose boundaries are not entirely clear. However, it is crucial to understanding his motivational theory and to identifying an unusual virtue he calls “strength of mind,” the motivational prevalence of the calm passions over the violent. In this paper, I investigate the boundaries of the calm passions and consider the constitution of strength of mind and why Hume regards it as an admirable trait. These are provocative issues for two reasons. (...) First, it seems as though one might exhibit the prevalence of calm over violent passions, even if the prevailing calm passions are vicious traits of character. Second, the natural virtues for Hume are non-moral motives that garner approval for the effects they tend to produce. But strength of mind is unique in that it is not defined in terms of a particular motive, but in terms of the causal force (strength) of any number of motives in competition with others. (shrink)