We asked the musicians about what makes each part of a string quartet unique—here’s what they had to say.

Watching a great athlete, performer or surgeon at work is mesmerizing. When a highly complex skill looks effortless, we tend to think of the performer as otherworldly, rather than as the result of years of dedicated, mundane training. Effortless mastery, the hallmark of the world-class athlete, surgeon or other performer, appears only after countless hours of what’s now widely called deliberate practice.

These past few weeks, I’ve been taking a break from professional performances and have indulged in practicing just for the love of it. Musicians don’t always have the luxury to work on pieces that aren’t about to be performed, since the life of a musician is just as busy as any other demanding profession.