Cellist Yo-Yo Ma and pianist Emanuel Ax, by this point, have little left to prove. Indeed, the pair has recorded Beethoven's complete cello sonatas once before, in the 1980s, with the complete cycle set winning a Grammy Award and becoming one of the standard recordings for these works. Do they have something to add? Nothing revolutionary, but this new set is really a delight, with the kind of mutual understanding born of nearly a half-century of collaboration. Ma and Ax seem to be communicating in a deep way here, at both large and local levels. The overall mood is indicated by the title, taken from a note Beethoven supposedly attached to a copy of the Cello Sonata No. 3 in C major, Op. 69, that he sent to a friend. The story may be apocryphal (the note has never been found), but Ax says he wants to believe it, and the performances have a stirring, hopeful impact in the time of coronavirus when they were recorded. In the large structural scale, Ax refers to the contention of scholar Lewis Lockwood that these sonatas, far from being peripheral to Beethoven's output, were points at which he began to rethink major structural questions, and indeed Ax and Ma give weight to the dimensions of the early sonatas, the major incursion of counterpoint into the middle-period Op. 69, and the adumbrations of late Beethoven in the final two. At the local level, there is a remarkable sense of meditative conversation in the playing here. There is no way to fake this, and the seeming spontaneity is nothing less than gripping for the hearer. The only complaint here is the rather chilly sound of the recording venue, the Seiji Ozawa Hall at Tanglewood in Massachusetts. Perhaps it made the most sense with coronavirus restrictions in place, but at times, Ax's piano seems to get lost when one wants it to be front and center. This does not detract much, however, from a recording that will yield pleasures for years to come.