Jeremy Denk. (Michael Wilson)

Pianist Jeremy Denk, the recent recipient of a MacArthur Foundation“genius grant,” held a packed Kennedy Center Terrace Theater audience spellbound Saturday afternoon in a bardic traversal of Bach’s “Goldberg Variations.” One of the highest peaks in all music, not just keyboard music, this behemoth (more than 70 minutes long) has been offered several times in recent seasons by the Washington Performing Arts Society, which apparently felt there cannot be too much of a good thing, because here it was again.

Denk, who is almost as well known for his wry, slightly subversive blog and his lively writings in the New Yorker, has the “Goldberg” deep in his corpuscles; the technical mastery was such that he could give full play to an unending stream of ideas, some almost certainly coming on the fly.

Each of the 30 variations is in two parts, and each part is to be repeated. Denk’s rethinking and reexamining on the repeats (though he omitted a few) was a source of constant delight; although the music is too contrapuntally dense to admit much in the way of added ornamentation, there’s an endless number of different meanings depending on which line(s) to emphasize, how phrases can be shaped through dynamics, etc.

Denk projected the piece as a journey of the soul, into darkness and back again; Variations 28 and 29 were among the most dazzlingly optimistic and the reprise of the aria was ever so slightly faster — nostalgic but simpler. Again, the panoply of ideas was bracing, even startling at times.

Denk’s pianism reveals great art and much hard work, though there are areas where he could yet improve. The dynamic range is wide, but the touch less so. Denk’s articulations could be more varied, especially on the crisp side. There was some labored passagework in the virtuoso variations such as Nos. 5, 14 and 20. And rubato works best when the basic pulse is left alone, letting the melody go its way now and then; Denk’s rubato was at times a little Chopinesque. These are minor quibbles, admittedly. He is an artist of uncommon communicative ability, whose playing gives as much intellectual as sensual pleasure.

As heavy a meal as “Goldberg” was, Denk added an appetizer at the last minute: Mozart’s Piano Sonata No. 15 in F, K. 533/494. This is a work of rare disquiet, even for Mozart — the andante contains music that could pass for Shostakovich or Mahler. Denk navigated through the thickets with sensitivity and unruffled control.

Battey is a freelance writer.