The total number of Scarlatti's secular operas was more than one hundred and fifteen. He composed many oratorios, among which may be mentioned "I Dolore di Maria," "Il Sacrafizio d'Abramo," "Il Martirio di S. Teodosia," "La Concezzione della Beata Virgine," "La Sposa di Sacra Cantici," "S. Fillipo Neri," "La Virgine Addolorata," etc. There were about two hundred masses, and more than four hundred secular cantatas. The latter are semi-dramatic settings of short texts for a single voice, with accompaniments for clavier, or combinations of instruments for chamber use. The vast number of pieces of the latter class, together with many other compositions nearly allied to them (chamber duets for voice and light accompaniment, etc.), can only be regarded as having been occasioned by special circumstances in the way of facilities for performance. For it must be remembered that nearly all of these works demand of the singer a degree of virtuosity which was then extremely rare, and to be found perhaps scarcely at all outside the pupils of Scarlatti himself. The solution is to be found in the fact already mentioned that the master himself was a fine singer. Furthermore he had a daughter, La Flaminia, who seems to have been a singularly gifted creature. Bernardo de Domenice, in Vol. IV. of his "Vite d'Pittori, Scultori, ed Archetetti napolitain" (Lives of the Painters, Sculptors, and Architects of Naples), is quoted by Florimo, in his "La Scuola Musicale di Napoli" (Marano, 1880), as saying of Francesco Solimene, that he was a lover of music, and in the habit of spending much time at the house of Scarlatti, whose daughter La Flaminia was a wonderful singer, full of dramatic fervor and gifted with a magnificent voice. It would seem, therefore, that these works may have been composed primarily for his own satisfaction and for the pleasure of his own family circle. In respect to the facility with which he composed, as well as in the agreeable manner of writing for the voice, Scarlatti was the true founder of later Italian opera, his principles of composition having been almost universally followed until past the middle of the present century. But unlike some of the modern Italians, Scarlatti's ease of production rested upon most thorough attainments in counterpoint and the technical mastery of material. His great masses are monuments of learning, and by good judges are counted worthy of being placed beside those most honored in the annals of ecclesiastical music. Among the most celebrated of these works are a four-voice requiem, an "Ave Regina Cælorum" for two voices and organ, a great four-voice canon, a five-voice mass with orchestra, a great pastoral mass for two choirs, eleven voices, with orchestra and organ, and a famous motette, "Tu es Petrus," for two choirs. This was sung at the coronation of Napoleon I. by a choir of thirty papal singers, specially imported for the purpose.