Beethoven explored many genres throughout his career, but he continually returned to the piano sonata, writing 32 between 1795 and 1822, with the first 15 arriving by 1801. As with much of his early work, the influence of Haydn and Mozart was clear, but as time passed Beethoven carved out his own sound. Few bodies of work contain so many canonical entries, spanning the Moonlight sonata of 1801 to the technically demanding Hammerklavier of 1818.