Cello1750 wrote:
I read in an interview that he said he always taught his students to play with curved fingers, presumably for architectural strength, until he saw a video of himself playing and noted that he himself played consistently with flat fingers. It's amazing to watch -- I don't know how he does it, but he certainly does. Did.

 True. He could really drop the hammer down when he needed powerful attacks. But he also had the artist's touch, as we hear. 

Flat fingered vs. curved fingers is also a cello issue. I think one should utilize both, or, one would normally arrive to a mixed approach when searching for colors on a cello.