Atmanam rathinam vidhi
Shareeram rathameva tu
Budhim tu sarathim vidhi
Manah pragrahamevacha
Indriyani hayanyahur
Vishayansteshu gocharan
Atmendriya manoyuktam
Bhoktetyahur maneeshinah
- Kathopanishad
A model for the working of the principle through the intellect, mind and body is described here. Know the spirit within as the sole passenger sitting in a chariot. The chariot is the body associated with that spirit. The intellect sits in the driving seat and controls the horses harnessed to the chariot. Mind is the reins by which the charioteer gets hold of the horses, to make them perform in accordance with its will.
The sense organs are the horses. The objects in this universe keep pulling the sense organs towards them. The intelligent persons understand that the inner spirit is the true consummator of all objects. The spirit acts through the mind to reach the objects through the sense organs.