DEFINITIONS OF HAPPINESS.
1. The (Aristotelian) ideal of living well and happiness are (practically) identical. Should we, on that account, grant even to animals the privilege of achieving happiness? Why might we not say that they live well, if it be granted them, in their lives, to follow the course of nature, without obstacles? For if to live well consist either in pleasure (pleasant passions, as the Epicureans taught), or in realizing one's own individual aim (the Stoic ideal), then this living well is, in either case, possible for animals, who can both enjoy pleasure, and accomplish their peculiar aim. Thus singing birds live a life desirable for them, if they enjoy pleasure, and sing conformably to their nature. If further we should define happiness as achieving the supreme purpose towards which nature aspires (the Stoic ideal), we should, even in this case, admit that animals share in happiness when they accomplish this supreme purpose. Then nature arouses in them no further desires, because their whole career is completed, and their life is filled from beginning to end.