BG Chap 18 - Sanjaya describes the conversation he heard

Sañjaya said that having heard this astonishing conversation between Vāsudeva and Arjuna, his hairs were standing on end. The conversation was astonishing because it had never before appeared among men. By the mercy of Vyāsadeva, Sañjaya was able to hear this most confidential knowledge of bhakti yoga which reveals the Supreme Lord, directly from the master of all mysticism, Kṛṣṇa. By the mercy of Vyāsa, Sañjaya attained a form with transcendental eyes and ears, and thus was able to hear the conversation from Kṛṣṇa’s own mouth. This means that one has to understand Kṛṣṇa not directly but through the medium of the spiritual master. The spiritual master is the transparent medium, although it is true that the experience is still direct. This is the mystery of the disciplic succession. When the spiritual master is bona fide, then one can hear Bhagavad-Gītā directly, as Arjuna heard it.

Remembering this wonderful and holy conversation again and again, Sañjaya took great pleasure being thrilled at every moment. This conversation destroys all faults of the hearer, and destroys even avidyā – the cause of material existence. The result of Kṛṣṇa consciousness is that one becomes increasingly enlightened, and he enjoys life with a thrill, not only for some time, but at every moment. Sañjaya was filled with wonder remembering the amazing form of Lord Hari, the universal form, and he rejoiced again and again.