Opera seria had its weaknesses and critics.
The taste for embellishment on behalf of the superbly trained singers, and the use of spectacle as a replacement for dramatic purity and unity drew attacks.
Francesco Algarotti's Essay on the Opera (1755) proved to be an inspiration for Christoph Willibald Gluck's reforms. He advocated that opera seria had to return to basics and that all the various elements—music (both instrumental and vocal), ballet, and staging—must be subservient to the overriding drama. In 1765 Melchior Grimm published "Poème lyrique", an influential article for the Encyclopédie on lyric and opera librettos.