I have laboured carefully, not to mock, lament, or execrate, but to understand human actions; and to this end I have looked upon passions, such as love, hatred, anger, envy, ambition, pity, and the other perturbations of the mind, not in the light of vices of human nature, but as properties, just as pertinent to it, as are heat, cold, storm, thunder, and the like to the nature of the atmosphere, which phenomena, though inconvenient, are yet necessary, and have fixed causes, by means of which we endeavour to understand their nature, and the mind has just as much pleasure in viewing them aright, as in knowing such things as flatter the senses