Published in Amsterdam in 1725, Vivaldi’s The Four Seasons are early examples of the concerto form: a musical structure designed to show off the virtuosity of the solo instrument, which in this case is the violin.
Concertos typically have three ‘movements’: self-contained sections, each characterised by a particular tempo or mood. The most common pattern for concertos was to begin and end with fast, upbeat movements, and have a slower, more poetic movement in between.
Before Vivaldi, the solo line in a concerto was more like a musical decoration; in Vivaldi’s concertos, the contast between full orchestra and solo instrument becomes the key element in the structure of the whole piece, with the orchestra acting as a musical refrain or chorus (the ‘ritornello’) which alternates with a series of contrasting verses featuring the soloist.
With his concertos, Vivaldi set new standards for virtuosity, requiring soloists to play faster and more difficult music than ever before. He also introduced some striking musical effects in the orchestral writing; for example, he sometimes has all the orchestral instruments playing the same tune, in unison; you can hear this effect in the ‘storm’ music in the first movement of Spring, and at the beginning of the third movement of Summer.