first the director in 1702, and was not at various times from then to 1717, almost each time due to political instabilities. From 1703 to 1709, Keiser changed the opera house from being a public institution to a commercial venture with two to three performances a week, in contrast to the opera houses intended for the nobility.

He helped transition opera from the mid-Baroque to the late-Baroque. He introduced a more varied type of aria into his operas, with more passive arias, and also faster arias being introduced into his bilingual and