In the quotation below, Giovanni Battista Mancini elucidates on his training with his teacher Leonardo Leo.

Leo was a pupil of Fago at Santa Maria della Pietà dei Turchini. His first opera was performed in 1714. In 1723 he turned to the Neapolitan commedia musicale form, and became one of the leading composers of comic opera. He taught at two of the conservatories in Naples at various times. Leo was Mancini’s first teacher.

This great man was accustomed to write every three days a new solfeggio for each of his scholars, and with reflection to adapt it to the strengths and abilities of each. Among my colleagues there were some of greater age than my own, and consequently more formed and more robust of chest. So the diligent and loving master wrote for these, things of greater style for sustaining and style for agility of voice: I was desirous of emulating my companions without ever reflecting, and one morning when the master presented me with a new solfeggio, I observed that it did not extend beyond the usual system, and taking courage, I said: ‘Signor, I believe I can sing the solfeggios of my other colleagues, although they are of greater age than I, and execute them equally well’; the great master, who had weighed my strengths with the shrewdness of his understanding, and having penetrated further than I was able, or could; and wishing to correct me to my profit and cut off the head of my capricious presumption; suavely granted my wish.

I began the solfeggio earnestly, and everything went well at first; but, what is this? I became like a baby who undertakes a course of action without measuring his strength, thereby losing his breath and falling to earth with a heavy thud. The other things which were more difficult, as much to sustain as to graduate, I knew in that moment to be beyond my ability to execute, because art and strength had abandoned me: then the master with a smiling face turned to me: ‘I have admired,’ he said, ‘your desire; I praise it, but I cannot follow it, because it would upset the order of your studies, and would be your downfall; continue to study with method and patience and in time you will join your companions, and equal them with great glory.’

Mancini, Giambattista. “Practical Reflections on Figured Singing, 1774, 1777.” (1996).