Have you ever wondered why the words ‘motion’ and ‘emotion’ are so similar even if they mean completely different things? Actually they do refer to closely related phenomena: unlike plants, animals have the ability to move according to the commands dictated by their nervous system; they (hence, we) move because of the need to maintain the living existence. That doesn’t happen to plants: they just remain in the same place and preserve existence by absorbing from the milieu the nutrients they need. Motion is a pursuit (or flight) towards (or away from) an object, and the animal, in the process of making sense of the outward world she/he has produced as a consequence of his/her self-identification as a motile living being, desires (or fears) that object. Moreover, motility allows a new mode of existence, in which space is transformed into a dimension of freedom rather than of dependence. Now it becomes clear the role of emotion: it is the feature of the animal soul that allows a proper use of this new dimension of spatial freedom to achieve the continuation of life. In other words, emotion and motion are two forces, the former driving in time the latter, it’s spatial counterpart.
What does etymology says about this? Emotion comes from ex-motion, and ex means “out of”. Thus, etymologically speaking, emotion means “what is created from movement”. Now everything makes sense. Q.E.D.