When I started reading this article I didn't notice the byline, figuring it was one of the NYT's music critics. As I got further into it, I wondered how a critic could know so much about how Leonard Bernstein lived, how dedicated he was to the show that was his life, how completely he put himself at the service of music, how frustrating it was for him to think constantly that he wasn't composing enough, and might not leave a real legacy. So I flipped back and saw that it was written by Michael Tilson Thomas, a distinguished conductor himself (I remember when he was a young lion, aware of him being at USC the same time I was at UCLA; he's a year younger than I, so he's not young any more, except perhaps at heart) and one of many musicians Lennie mentored and encouraged and in some ways taught.
Those who have never been into classical music as much as a nut like me, or those who are too young to have experienced through various media the force of Leonard Bernstein's personality and musicality might find here some of the reasons that he loomed so large in American musical life. For those who want a more detailed view, written at something of a low point in his life, I found Meryle Secrest's 1994 book "Leonard Bernstein: A Biography" quite engrossing