Retrospection shows us that there were originally three distinct divisions in opera: the _recitativo_, the _aria_, and the _ritornello_. At first the _ritornello_ was but the repetition of the cadence, but developed subsequently into a transitory period intended to complete an unfinished vocal phrase or to describe the action on the stage. Later, a union of these three distinct divisions resulted in the _arioso_, or fragmentary _cantilena_ joined to _recitativo_. The _parlante_ or musical declamation over a melodic phrase in the orchestra originated in opera-buffa as developed by Piccini and Paesiello; subsequently Spontini transplanted it into serious opera. It is equivalent in spoken drama to melodramatic recitation. Wagner's style is therefore nothing more than an additional link in the chain of natural evolution. The pith of Wagner's ideals may be summed up by saying that he aimed to substitute a noble form of art in the place of mere pleasure-giving and sensational fabrications. Music, poetic ideas, action and stage setting were all to be worthy of the subject intended for presentation. His choice of subject for dramatization was restricted to such as could embody characters capable of being treated morally and intellectually as well as æsthetically. Wagner above all others defined the true mission of German national art and guided her to a tangible realization of that mission. IV. Wagner's operas and music dramas may be divided into either of two general classifications. The first treats of the musical contents and structural form of his dramas, and of the evolution of his philosophical ideas. The second relates solely to differentiated style of orchestration and numerical distribution of instruments.