The internet never ceases to amaze me. Getting to witness a master class of one of the greatest violinists of all time some 50 years after the fact is pretty remarkable.
Here is a master class in four parts that the great Jascha Heifetz gave at USC in 1962. The intensity he portrays in this class reminds me of how he played the violin.
My favorite comment from the class: "You're playing it too safe."