Carry away a man's intelligence
Bhagavad-gita As It Is
BG Chapters 1 - 6
Even one of the roaming senses on which the mind focuses can carry away a man's intelligence.
BG 2.67, Translation and Purport: As a strong wind sweeps away a boat on the water, even one of the roaming senses on which the mind focuses can carry away a man's intelligence.
Unless all of the senses are engaged in the service of the Lord, even one of them engaged in sense gratification can deviate the devotee from the path of transcendental advancement. As mentioned in the life of Mahārāja Ambarīṣa, all of the senses must be engaged in Kṛṣṇa consciousness, for that is the correct technique for controlling the mind.
Lectures
Bhagavad-gita As It Is Lectures
Even one of the senses in which the mind becomes fixed can carry away a man's intelligence.
Lecture on BG 2.62-72 -- Los Angeles, December 19, 1968:
Tamāla Kṛṣṇa: 67: "As a boat on the water is swept away by a strong wind, even so, one of the senses in which the mind becomes fixed can carry away a man's intelligence."
Prabhupāda: Yes. If you... Suppose on the Pacific Ocean you are on a boat or on a nice seat, but if you have no controlling capacity, one wave of that Pacific Ocean can immediately bring you to the bottom of the sea. So this is required. We are in the midst of the Pacific Ocean of this māyika world. Saṁsāra-samudra. It is called samudra. So at any moment our boat can be topsy-turvied if we have no controlling power. Yes.