Since, then, choice, as was said before, is concerned with the goods that contribute to the end and not with the end, and with the things that are possible to us, and with such as afford ground for controversy as to whether this or that is desirable, it is evident that one must have thought and deliberated about them beforehand; then when a thing appears best to us after having thought it over, there ensues an impulse to act, and it is when we act in this way that we are held to act on choice.