when they started in 1945 their cellist was mstislav rostropovich. rudolf barshai was their viola player. very soon afterwards rostropovich found he had too many other engagements, so he got valentin berlinsky to be their cellist. the four men who then formed the quartet signed an oath in their own blood that they would be faithful and stay together as a group. they stayed together for 20 years. then rostislav dubinsky, the first violinist, defected to the west and the second violinist, jaroslav alexandrov, retired because of bad health. with two new players, the quartet spend two years practising together before they performed again in public.