Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 23

Sanskrit:

अद‍ृष्टादश्रुताद् भावान्न भाव उपजायते ।असम्प्रयुञ्जत: प्राणान् शाम्यति स्तिमितं मन: ॥ २३ ॥

ITRANS:

adṛṣṭād aśrutād bhāvānna bhāva upajāyateasamprayuñjataḥ prāṇānśāmyati stimitaṁ manaḥ

Translation:

Because the mind is not disturbed by that which is neither seen nor heard, the mind of a person who restricts the material senses will automatically be checked in its material activities and become pacified.

Purport:

It may be argued that even while closing one’s eyes, while dreaming or while living in a solitary place, one may remember or contemplate sense gratification. Such an experience, however, is due to previous sense gratification that one repeatedly saw and heard about. When one restricts the senses from their objects, especially from intimate contact with women, the mind’s material propensity will slacken and, like a fire without fuel, eventually die.