Bhagavad Gita · Chapter 2: The Path of Understanding

Bhagavad Gita 2.58

yadā saṃharate cāyaṃ kūrmo'ṅgānīva sarvaśaḥ | indriyāṇīndriyārthebhyastasya prajñā pratiṣṭhitā ||

When a person withdraws the senses from their objects on every side, as a tortoise draws in its limbs, that person's wisdom is firmly established.

Modern context

A tortoise draws in its limbs at will and puts them out again when it is safe. The image is of control, not of permanent retreat. The steady person can withdraw attention from sights, sounds and screens when they choose, and engage again when they choose. The skill is in being the one who decides.