[Sidenote: =Points of difference=] If we take the operas of the first few years of the seventeenth century, what do we find? That the form of tonality in use was the mode and not the scale; that time (_i.e._, measured music), as we now know it, did not exist; that harmony, as we now know it, did not exist; and that the instruments of the orchestra (although some have survived), were in the main instruments which have fallen into disuse, many of them having no modern counterparts. It needs little pointing out that this form of opera must have sounded very different to its successors. [Sidenote: =Monteverde’s innovations=] The next important innovations, generally accredited to =Monteverde=, include the dramatic effects of _pizzicato_ and _tremolo_ passages for the stringed instruments—devices which have been used with the happiest results by all composers of subsequent date. Such devices, unknown in church music anterior to this time, or even in the music written for instruments only without voices in the church style, are most effectively employed for the illustration of certain situations on the stage: the mere introduction of these alone is sufficient to separate this school of opera from that which preceded it. [Sidenote: =Use of Orchestra=] But Monteverde’s inventions or adoptions did not stop here, for it was he who first added many instruments to the orchestra; not only did he employ additional instruments, but he used them in such a way as to wed certain characters or situations to music in which certain sets of instruments were employed, thus anticipating the much later Wagnerian device of accompanying certain ideas by a fixed theme, or by particular combinations in the orchestra. [Sidenote: =Adoption of Melody=] So far the music of the opera was confined to recitative: that is, to the musical rendering of the dialogue without regular rhythm or melody. Another period of opera opened out altogether, when composers began to adapt portions of the dialogue to regular formal melody of a rhythmic nature, and in the diatonic scale, much as we now know it. Credit for this is generally given to =Cavalli=, and his example was followed by a well-known early opera writer, =Alessandro Scarlatti=. The recitative of the latter took, too, a richer shape and form, inasmuch as it was now often accompanied by the whole of the orchestra, instead of merely by the continuous bass, completed by harpsichord harmonies. [Sidenote: =Birth of the Aria=]