The Compendium of Caraka 4.1.76

4.1.76

cetanāvān yataścātmā tataḥ kartā nirucyate/
acetanatvācca manaḥ kriyāvadapi nocyate//

Because the self is conscious, it is therefore called the agent; / and because of being devoid of consciousness, the mind, although possessed of action, is not so called.