Now let me show you how emotions start, grow stronger, and take over. The first stage happens without your choice. It's like a warning that an emotion is coming. The second stage includes a desire, but not a stubborn one. For example: "I should get revenge because someone hurt me" or "This person deserves punishment because they committed a crime." The third stage is already out of your control. It overpowers reason and wants revenge no matter what — not because it's right, but just because. We can't use reason to escape that first mental reaction any more than we can escape certain physical reactions. We can't stop ourselves from yawning when others yawn. We can't help blinking when fingers suddenly dart toward our eyes. Reason can't overcome these habits, though practice and constant awareness might weaken them. These automatic reactions are different from emotions that start and end through deliberate thought.
Furthermore, that you may know in what manner passions begin and swell and gain spirit, learn that the first emotion is involuntary, and is, as it were, a preparation for a passion, and a threatening of one. The next is combined with a wish, though not an obstinate one, as, for example, “It is my duty to avenge myself, because I have been injured,” or “It is right that this man should be punished, because he has committed a crime.” The third emotion is already beyond our control, because it overrides reason, and wishes to avenge itself, not if it be its duty, but whether or no. We are not able by means of reason to escape from that first impression on the mind, any more than we can escape from those things which we have mentioned as occurring to the body: we cannot prevent other people’s yawns temping us to yawn:[3] we cannot help winking when fingers are suddenly darted at our eyes. Reason is unable to overcome these habits, which perhaps might be weakened by practice and constant watchfulness: they differ from an emotion which is brought into existence and brought to an end by a deliberate mental act.