When Kṛṣṇa (Krishna) was going back to Dvārakā (Dwaraka) after the war of Kurukṣetra (Kurukshetra) [we find this episode in Āśvamedhikaparva (Aswamedhikparva) of Mahābhārata (Mahabharata)], Arjuna took him aside and said, “Kṛṣṇa, you lectured me on the essence of Gītā (Gita) at the beginning of the great war in order to clear away my confusions. But unfortunately I have forgotten much of those lessons after so many days and events. I am curious about them yet now. Pray tell me once again about them.”
Kṛṣṇa was annoyed with his best friend and told him, “It does not please me at all to hear that you have forgotten the philosophical lessons of momentous importance. You have not captured them in your heart with an unperturbed brain and a tranquil heart” – abudhyā nāgrahīryastvaṃ tanme sumahadapriyam. “And this is also true that, that lecture was one of a kind and I myself have lost the memory of each minute details of it. At that time I had my conscience concentrated on the Supreme Being, detached from this living world, and lecturing you on the Supreme Being and the connection of the mortal world with Him – I was lecturing with great spontaneity – it is never possible to deliver a second lecture exactly in that way” – na śakyaṃ tanmayā bhūyastathā vaktumaśeṣataḥ/ paraṃ hi brahma kathitaṃ yogayuktena tanmayā.
However, thereafter Kṛṣṇa did lecture Arjuna on some significant philosophical topics. This lecture, spanning from the sixteenth to the ninety-second chapter of Āśvamedhikaparva, is known as Anugītā (Anugita).