Precisely how they go about producing a unified conception in the music they play is, however, a complex process that varies from ensemble to ensemble, performance to performance. Still, most musicians agree that a string quartet will not make it over the long haul if its players cannot sustain a consistent degree of internal harmony, both personal and musical. Other quartets go on for many seasons with no subtractions or additions. Consider the Guarneri String Quartet, one of America's finest, which flourishes with the same four members it had when it was founded 36 years ago. Think of the Amadeus, Europe's foremost string quartet since its inception in 1947, which kept its original roster intact into the 1980s.
Different musicians have different reasons for leaving quartets.
Some retire, like Robert Mann, the Juilliard Quartet's veteran first violinist and paterfamilias. Some die, like Pierre Menard, second violin of Chicago's Vermeer Quartet, who was replaced by Matthias Tacke. Hersh appears to be one of a different category of artists who find themselves no longer able to make music successfully under the often painfully intense conditions under which string quartets must operate. Sometimes they are in deep denial and the painful truth has to be pointed out to them by their colleagues. I wouldn't be surprised if Hersh feels the same way.