Bhagavad Gita · Chapter 2: The Path of Understanding

Bhagavad Gita 2.60

yatato hyapi kaunteya puruṣasya vipaścitaḥ | indriyāṇi pramāthīni haranti prasabhaṃ manaḥ ||

For the turbulent senses, Arjuna, forcibly carry away the mind even of a discerning person who is striving.

Modern context

Krishna is frank about how hard this is. Even a wise person who is making a sincere effort can have the mind swept away by the senses. It is useful to hear that from the teacher himself: a lapse does not prove you are unfit. It proves the senses are strong, which everyone who has tried already knows.