The operas of Johann Adolf Hasse, and the type of poetic drama created by Metastasio and copied by Hasse's other librettists, are argued to be dramatically viable because of their derivation from Italian popular comedy, because of their classicism which makes them formally and stylistically conservative and perpetuates the clear distinction of recitative and aria, and because of the meticulous respect for the text shown by the composer. Contemporary writers are the basis for criticism. Marpurg's essay on simple recitative forms the basis for a discussion of this medium, which is found to be subtly expressive in its harmony and vocal intervals: recitative can be "historic" or "pathetic", the latter type characterized especially by the interval and chord of the diminished seventh. Musical phrases may be echoed or heard in sequence, always to make some dramatic point; note values are chosen to hurry or slow the pace of delivery; aria themes often grow out of phrases in the recitative. The principal development in recitativo stromentato is in its dramatic purpose.