Complex sentence: He initially studied in his native Pistoia, under Innocenzo Spinazzi, the the patronage of the Grand Duke Leopold sustained him as a pupil of Agostino Penna in Rome.
Split into simpler sentences: He initially studied in his native Pistoia, under Innocenzo Spinazzi. Later, the patronage of the Grand Duke Leopold sustained him as a pupil of Agostino Penna in Rome.