BG 3.40-42
The senses, the mind and the Reason are said to be its seat; by these enveloping wisdom, it bewilders the dweller in the body. Therefore, O best of the Bhâratas, mastering first the senses, do thou slay this thing of sin, destructive of wisdom and knowledge. It is said that the senses are great; greater than the senses is the mind: greater than the mind is the Reason; but what is greater than the Reason, is He.