Mahabharata 12.240.3

बुद्धिरात्मा मनुष्यस्य बुद्धिरेवात्मनोऽऽत्मिकायदा विकुरुते भावं तदा भवति सा मनः

buddhirātmā manuṣyasya buddhirevātmano''tmikāyadā vikurute bhāvaṃ tadā bhavati sā manaḥ

Our plain-language meaning of this verse is waiting for scholar review.