Could you tell me why it is "a very first", not "the very first"?
"A very first encounter" is used here to refer to the idea of first encounters in general. He does this to compare this specific first encounter of the tiger cubs meeting the adult tiger with other first encounters in general. If he had used "the very first encounter" here, it would express that he is referring only to this event of the cubs meeting the adult tiger, and not comparing it with any other first encounter events.
Get more Native English Expressions >