The teaching of Carl Czemy was influential in the first half of the nineteenth century. His Complete Theoretical and Practical Piano Forte School and its supplement, The Art ofPlaying the Ancient and Modern Piano Forte Works, are especially relevant to the performance of Beethoven's piano sonatas. Much of the information in this monumental treatise reveals how Beethoven would have performed his sonatas. His pedalling techniques, for example, are similar to those described in Czerny's treatise. Although The Art was published in 1846, some of the ideas in tl-ds book date back to Czemy's Haslinger II edition of the late 1820s, thereby showing a. certain consistency over a period of about twenty years. Most of Czemy's teaching on the performance of Beethoven's piano sonatas, hs recorded in his piano treatise, stem from Beethoven's own practice. However, he sometimes altered Beethoven's directions because he considered his solution to be better (such as the fingering. in the trio of Op. 2/l/iii), or because they did not conform to contemporary performing styles, or simply because they did not suit the more resonant pianos of his day.