Antonio Vivaldi's (1675-1743) four-hundred and fifty surviving concertos remain today the model for the Baroque concerto. Indeed, J.S. Bach himself learned the genre by copying the concertos of Vivaldi by hand. To effect a Concertante Vivaldi uses every conceivable combination of instruments. The Four Seasons is a group of four concertos grouped together each reflecting a season of the year. Such fanciful things aside, they are essentially violin concertos. Vivaldi develops the ritornello form by alternating complex solo passages with an orchestral "ritornello" theme. No where is this better demonstrated than the Spring Concerto.