Pianist Easley Blackwood, who’s taught at the University of Chicago for more than three decades, is something of both a recluse and an eccentric. His reclusiveness may explain why he rarely gives solo recitals and is only an occasional member of the Grammy-winning Chicago Pro Musica. His eccentricity surely accounts for his choice of repertory, with its disproportionate share of unclassifiable and gleefully difficult late-19th-century and 20th-century pieces. Take the centerpiece of Blackwood’s first solo appearance in many a year: Ives’s Second Sonata, subtitled “Concord, Mass. 1840-1860.” The notoriously demanding work–a complex web of ideas under the guise of musical sketches of transcendental thinkers Emerson, Hawthorne, the Alcotts, and Thoreau–daunts most pianists. (The last live performance of it I heard, in fact, was given by Blackwood more than 15 years ago.) Having devoted years to learning the music, Blackwood arguably is the only interpreter who’s managed a lucid and coherent account (now available on the local label Cedille Records). Also on the bill are Sonatina (1916), an ersatz avant-garde fancy by the influential Italian composer Alfredo Casella, and Karol Szymanowski’s Masques (1916), whose movie-music essence is heightened by episodic allusions to Scheherazade, Tristan, and Don Juan. Blackwood will return in a joint recital (with cellist Kim Scholes) on February 21 performing Frank Bridge’s Sonata (1917) and his own (1985), among others. Tonight at 8; Mandel Hall, University of Chicago, 1131 E. 57th; 702-8068.