Mahabharata 12.217.28

कौमारमेव ते चित्तं तथैवाद्य यथा पुरासमवेक्षस्व मघवन्बुद्धिं विन्दस्व नैष्ठिकीम्

kaumārameva te cittaṃ tathaivādya yathā purāsamavekṣasva maghavanbuddhiṃ vindasva naiṣṭhikīm

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