In general, Beethoven's earliest compositions show his struggles to master the prevailing classical style, both in structural and idiomatic terms. Several works, including two he later published, show the incipient signs of his later individual style: twelve Lieder, several of which he published in 1805 as Opus 52, his Wind Octet, later published as Opus 103, and several sets of Variations, including one (WoO 40) for violin and piano on Mozart's aria "Se vuol ballare" (later reworked in Vienna). Although these works largely conform to the formal conventions of the classical style, including a strict observance of form and, in the variations, the decorative filigree associated with the genre, they also show early signs of Beethoven's later tendency to more substantive treatment of thematic material.