Why: Sanjaya says he heard this wondrous dialogue between Krishna and the great-souled Arjuna, causing his hair to stand on end, stepping outside the direct conversation to describe his own experience of having witnessed it.

In life: sometimes the person who witnessed or reported on a significant exchange between two other people is genuinely, personally affected by what they observed, not merely a neutral, unaffected recorder of events.

Teaching: notice when you've been genuinely, personally affected by witnessing an important exchange between two other people, even as an outside observer, that impact on you is real and worth acknowledging, not something to dismiss simply because you weren't a direct participant.