Know the Self as Lord of the chariot, the body as the chariot itself, the discriminating intellect as the charioteer, and the mind as the reins. The senses, say the wise, are the horses, selfish desires are the roads they travel. 

Katha Upanishad

The Upanishads say that your body is like a chariot drawn by five powerful horses, the five senses. These horses travel not so much through space as through time. They gallop from birth towards death, pursuing the objects of their desire. The discriminating intellect is the charioteer, whose job it is not to drive you over a cliff. The reins he holds are the mind – your thoughts, emotions, and desires.

This image is packed with implications. For one, the job of the intellect is to see clearly. The job of the mind is to act as reins. When everything is working in harmony, our highest Self makes all the decisions. The intellect conveys these decisions to the mind, and the senses obey the mind. But when the senses are uncontrolled, they immediately take the road they like best: personal satisfactions, mostly pleasure. Then we are not making the decisions; the horses are.

Words to Live By: Inspiration for Every Day – Eknath Easwaran

The homework is to study and learn how to practice pratyahara. “In Sanskrit, pratyahara literally means “to draw toward the opposite.” The normal movement of the senses is of flow outward, where they encounter the objects of the world and name and interpret them with the aid of thought. The yogi simply observes the fact. “It is raining”, she may think or say, without desire or judgement. The yogic purpose of pratyahara is to make the mind shut up so we can concentrate. It is a long and patience-demanding apprenticeship in detachment. It is the gradual involution of the sense and stilling of the mind with the aid of breath to make the practitioner fit for concentration and meditation. One learns to watch the mind itself and its movements and ultimately to keep it stable and quiet.” Light on Life, BKS Iyengar (paraphrased)