KAṬHA UPANISHAD · 1.3.5

यस्त्वविज्ञानवान्भवत्ययुक्तेन मनसा सदा ।
तस्येन्द्रियाण्यवश्यानि दुष्टाश्वा इव सारथेः ॥ ५॥

yastvavijñānavānbhavatyayuktena manasā sadā ।
tasyendriyāṇyavaśyāni duṣṭāśvā iva sāratheḥ ॥ 5॥

Now he that is without knowledge with his mind ever unapplied, his senses are to him as wild horses and will not obey the driver of the chariot.