But in another sense energy is spoken of as passion. For energy is a movement in harmony with nature, whereas passion is a movement at variance with nature. According, then, to this view, energy may be spoken of as passion when it does not act in accord with nature, whether its movement is due to itself or to some other thing. Thus, in connection with the heart, its natural pulsation is energy, whereas its palpitation, which is an excessive and unnatural movement, is passion and not energy.