If purpose, then, is inherent in art, so is it in Nature also. The best illustration is the case of a man being his own physician, for Nature is like that - agent and patient at once.
AristotleOur virtues are voluntary (and in fact we are in a sense ourselves partly the cause of our moral dispositions, and it is our having a certain character that makes us set up an end of a certain kind), it follows that our vices are voluntary also; they are voluntary in the same manner as our virtues.
Aristotle