What’s a musician to do when his iPad goes blank in the middle of a concert?

I’ll tell you.

Because it happened last July at St. Paul’s Church in the midst of an audaciously good performance by cellist Alexander Hersh and pianist Evren Ozel.

I can’t recall if it was Debussy’s Cello Sonata, or Dohnanyni’s “Ruralia Hungarica,” or the Cello Sonata from Chopin.