It was thanks to his father's penchant for organizing musical concerts in his family's Berlin apartment on Sunday mornings that the 11-year-old Felix Mendelssohn began to compose quite a long series of string symphonies, and also that the works were initially performed. The study of music and composition spurred the young composer on greatly; his diligence as well as his youthful creativity developed early, and he made astonishing progress. In 1821, he wrote the first half of his string symphonies, which together took less than two years to complete. During performances that formed part of the concerts at home, he always took over the direction of the chamber orchestra, which consisted of amateur and professional musicians from the Berlin court orchestra.