“Just as rain penetrates an ill-thatched house, so defiling desires penetrate an uncultivated mind. Just as rain cannot penetrate a well-thatched house, so desire cannot penetrate a well-cultivated mind.”
Canonical Pali Original: Yathā agāraṃ ducchannaṃ, vuṭṭhī samativijjhati; Evaṃ abhāvitaṃ cittaṃ, rāgo samativijjhati.
— Gautam Buddha
The Awakened One, Founder of Dhamma
Pali Canon: Dhammapada 1.13-14 on guarding and training the mind through meditation and mindfulness.