David Hume, A Treatise of Human Nature David Hume, A Treatise of Human Nature , vol. Throw in a superior degree of probability to the side of grief, you immediately see that the passion diffuses itself over the composition, and tinctures it into fear. Encrease the probability and by that means the grief, the fear prevails still more and more, till at last it runs insensibly, as the joy continually diminishes, into pure grief. Here, Hume describes the movements of the passions as if they were colors of the prism bleeding into one another.
Emotion is described as a continual flow from one state to another.