Mantra 3

आत्मानꣳ रथिनं विद्धि शरीरꣳ रथमेव तु ।बुद्धिं तु सारथिं विद्धि मनः प्रग्रहमेव च ॥ ३ ॥

In plain words

Know ātman to be the rider of the chariot, and the body simply the chariot. Know buddhi to be the charioteer, and manas simply the reins.