L, It. sonare, = sound. Musical form, in its archetypal form one of the most important genres of the 18th and 19th centuries. A cyclic instrumental composition with several movements. The form is clearly structured from a harmonic and conceptual point of view and is subject to distinct rules. There are usually three movements, typically fast ? slow ? fast. In Beethovens case, however, there are sometimes two or four movements (in the case of the latter with the addition of a scherzo or minuet before the last movement). The most important movement is the first movement, which in the case of the Classical sonata follows sonata form. Often for piano or a melody instrument with piano accompaniment. Beethoven composed 32 piano sonatas with opus numbers, as well as four early piano sonatas without an opus number, ten violin sonatas, five cello sonatas and a sonata for horn.