1. Leonard Bernstein was originally born Louis Bernstein at the pressing wishes of his grandmother, but his parents and friends preferred to call him Leonard ("Lenny" for short). When Bernstein was 16, his grandmother passed away, which allowed him to have his name legally changed to Leonard.
2. He was born in Lawrence, Massachusetts to Russian/Jewish immigrants, and began playing piano at young age of five.
3. Bernstein's rise to fame was rapid. He was unexpectedly named Assistant Conductor of the New York Philharmonic with less than 24 hours' notice, when he was called upon to stand in for flu-stricken Bruno Walter. The program included works by Schumann, Miklós Rózsa, Wagner and Richard Strauss's Don Quixote with soloist Joseph Schuster, solo cellist of the orchestra. After a brilliant performance, he made the front page of The New York Times the following morning.
4. In a concert of Brahms' Piano Concerto No. 1, where he famously argued with the pianist Glenn Gould in rehearsal (Gould wanted a slower tempo), Bernstein made an announcement to the audience before they began: "Don't be frightened. Mr. Gould is here....in a concerto, who is the boss....the soloist or the conductor? The answer is, of course, sometimes one and sometimes the other, depending on the people involved." Ever the entertainer, who waited for the applause between each line of his address, Bernstein was later criticized for either attacking Gould or simply abdicating responsibility for the performance that was to ensue.
5. Perhaps his best-known work is the Broadway musical, West Side Story. Inspired by Shakespeare's Romeo and Juliet, the musical explored rivalries between two 1950's New York gangs (the Jets and the Sharks). What many don't know is that the musical was originally going to be about an Irish Catholic family and a Jewish family living on the lower east side of Manhattan. This idea was discarded, however, and replaced with the story we know and love today.
6. Bernstein was one of the first classical musicians to "master" TV. The Young People's Concerts existed in the US since 1924, but Leonard Bernstein brought them to a whole new audience in 1958 with the first televised concert of its type. Then, in 1962, The Young People's Concerts became a TV series, of which Bernstein conducted 53!
7. Bernstein was a close friend of Aaron Copland and recorded all of his orchestral works. He also played the Copland Piano Variations so regularly that they became his trademark piece.
8. He has been famously quoted saying, "I'm not interested in having an orchestra sound like itself. I want it to sound like the composer."
9. Though considered a conductor and great pianist, Bernstein oddly never performed a solo piano recital. He did, though, conduct and play in performances of Mozart piano concertos (and memorably in the Ravel Concerto in G).
10. Bernstein died only five days after retiring. His death was a result of emphysema.