The third step was his resounding entrance into the world of theater with the premiere in Vicenza in May 1713 of his first known opera, Ottone in villa. After this, he virtually conquered the theaters of Venice, taking control of the small San Angelo and San Moise theaters. The opera scores from this first Venetian period show sumptuous, exuberant works that bear the signs of an exceptional dramatic temperament. These innovative, disturbing compositions, which imposed the stilo nuovo as they clashed head on with the stile antico so appreciated by conservatives, earned him the animosity of a large segment of Venetian aristocracy, whose theaters never opened their doors to him. At the same time, Vivaldi also showed his talent in discovering excellent voices: he revealed many famous singers, such as Fabri, Merighi and Strada, well before Handel hired them to work in London.

Vivaldi also acted as an impresario during this period, in the purest sense of the term; he was a promoter of operas —his own, as well as those of other composers—that he revised or added to his own productions. An interesting account of this period of wild activity is found in the travel notes of a rich architect from Frankfurt, Johann Friedrich Armand von Uffenbach, who attended the Carnival season in San Angelo in 1715.

This music enthusiast gave his opinion of the sets and costumes, and admired the singers, saying that they ‘were incomparable and were in no way inferior to those of the great theater’, meaning those of San Giovanni Grisostomo. But he was especially astounded by Vivaldi, who dazzled him with his virtuoso violin playing. Uffenbach wrote in his notes, ‘Near the end, Vivaldi played a magnificent solo that he followed with an improvised cadence which truly astounded me, because it is hardly possible that anyone has ever played that well or ever will again. His fingers were a hairbreadth from the bridge, so there was almost no room for his bow, and he did this on all four strings with incredible sounds and speed.’ Vivaldi’s lyrical career developed as a kind of conquest guided by two watchwords: reform and surprise. This was a surprising yet premonitory meeting of art and marketing.

The fourth major stage of his career was the development of a structured activity as a private composer, executing many occasional, well-paid commissions for a network of customers and patrons. This involved instrumental music, with the sale of concertos specially written for or adapted to the commissions he received, secular vocal music, with the sale of opera arias, cantatas and serenate, and sacred music that Vivaldi began composing in the first decade of the 18th century: he composed sacred motets, hymns, psalms and concertos for various institutions. Two of his major sacred vocal works were written around this time: the famous Stabat Mater, in 1712 for a church in Brescia, and his first oratorio, La vittoria navale, performed in Vicenza in June 1713.

Throughout his entire life, Vivaldi combined these four parallel activities. While he gradually gave up the idea of printing his sonatas and concertos in individual opuses, to focus on collections or selling concertos to rich music lovers and patrons, he still published twelve opuses between 1703 and 1729. Two of these, opus IX, which contains twelve mature violin concertos, and opus X, which features works for solo flute, are inestimable masterpieces. His turbulent relations at the Ospedale della Pietà did not prevent him from being a temporary maestro di coro twice, in addition to being maestro di concerti and the official composer of instrumental music for its orchestra. These two periods of interregnum allowed him to compose some of his most beautiful sacred music, and the latest works, including a gallant revision of his Magnificat and his Beatus vir for two choirs, correspond to his final period of working with this institution, just before he left for Vienna.