Extolled by Chronicle music critic Joshua Kosman for his “strong, fearless execution,” “depth of feeling,” and “fiery elegance and formal command,” pianist Thomas Schultz returns to Old First Concerts in a program featuring two pillars of the piano repertoire: the Sonata in B flat, D. 960 by Schubert and Variations and Fugue on a theme of Handel, Op. 24 by Brahms.