science was received through the chain of succession and the saintly king understood in
that way (the way of Parampara).
But in course
of time the succession was broken, and therefore the science as it is appears to have been
He is talking about a method of knowing and calls it
knowing by parampara. Arjun is an intellectual.
He has been through the education system of the time and
was the best at the time.
Krishna is not only dealing with the best educated person
of the time but also with a brave heart of the time who also happens to be his sakha
And to him he says that there is another method of learning
that seems to have been lost. In the preceding shloka he has said that he told this yoga