The Nyāya Sūtras is an ancient Indian Sanskrit text composed by Akṣapāda Gautama, also known as Aksapāda, and is the foundational text of the pracina or Old Nyaya school of Hindu philosophy.
The text contains 5 parts divided further into chapter and contains over 500 sutras.
Babaji is reading from Nyāya-darśanam with the Vātsyāyana's bhāsya, which includes the Hindi commentary by Dhundhiraj Shastri.
All material relationships, whether of love or hate, will change; they will either fizzle out, turn to its opposite, change in intensity or come to end completely.