style became increasingly clear, and his works became more and more experimental, especially in genres like the piano sonata. By the period 1798-1802, his piano sonatas had become increasingly more experimental, but his Op. 18 string quartets and first symphony are more conservative then the sonatas, probably a symptom of his relative inexperience in composing in these genres in comparison to the piano sonata. Bonn period With the exception of a visit to Vienna in 1787, Beethoven lived in Bonn until 1792, where he worked in the court chapel of the Elector of Cologne. Some forty compositions from this period are extant, including ten early works written by the young adolescent Beethoven when he was being promoted as a child prodigy performer and published as a result of the efforts of his teacher. It has been suggested that Beethoven largely abandoned composition between 1785 and 1790, possibly as a result of a negative critical reaction to his first published works. A 1784 review in Johann Nikolaus Forkel's influential Musikalischer Almanack compared Beethoven's efforts to those of rank beginners. Whatever the case, most of Beethoven's earliest surviving works were written after he turned twenty, between 1790 and 1792. Some of this music was later published by Beethoven, or incorporated into later works. As such, they provide an important foundation for judging the later evolution of his style. Beethoven's early publications have been notable for scholars because of the view that it already indicated success as a child composer. One assessment stated that "if a child composer managed only a single published item, this might not indicate much, but if they had at least two publications, this is far more significant, for it suggests that the first one had had some success." Beethoven's childhood compositions had been published until 1784. An account cited how, by age thirteen, the child prodigy was already established, having composed three sonatas and four small works in addition to the earlier work called Dressler Variations. This is significant because, at this point, he no longer needed to be taught by a tutor, who would have influenced his musical style. 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,