Kaṭhopaniṣhad explains the differences in role of senses, mind, intellect, body and soul with the help of the model of a chariot:
ātmānagvaṁ rathinaṁ viddhi śharīraṁ rathameva tu
buddhiṁ tu sārathiṁ viddhi manaḥ pragrahameva cha
indriyāṇi hayānāhurviṣhayānsteṣhu gocharān
ātmendriyamanoyuktaṁ bhoktetyāhurmanīṣhiṇaḥ (1.3.3-4) [v21]
The Upanishad says there is a chariot, which has five horses pulling it; the horses have reins in their mouths, which are in the hands of a charioteer; a passenger is sitting at the back of the chariot. Ideally, the passenger should instruct the charioteer, who should then control the reins and guide the horses in the proper direction. However, in this case, the passenger has gone to sleep, and so the horses are running away.
In this analogy, the chariot is the body, the horses are the five senses, the reins in the mouth of the horses is the mind, the charioteer is the intellect, and the passenger seated behind is the soul residing in the body. The senses (horses) desire pleasurable things. The mind (reins) is not exercising restraint on the senses (horses). The intellect (charioteer) submits to the pull of the reins (mind). So in the materially bound state, the bewildered soul does not direct the intellect in the proper direction. Thus, the senses decide the direction where the chariot will go. The soul experiences the pleasures of the senses vicariously, but these do not satisfy it. Seated on this chariot, the soul (passenger) is moving around in this material world since eternity.
However, if the soul wakes up to its higher nature and decides to take a proactive role, it can exercise the intellect in the proper direction. The intellect will then govern the lower self—the mind and the senses—and the chariot will move in the direction of eternal welfare. In this way, the higher self (soul) must be used to control the lower self (senses, mind, and, intellect).