There is good evidence that several of the nineteen works that stand at the head of Diogenes' and Hesychius' lists were dialogues; it may be inferred with high probability, though not with certainty, that the others were so too, but Stobaeus, pp.
The Historia Augusta furthermore says that another lost work, Cicero's Hortensius, was allegedly modeled after the Protrepticus[4] and as the Hortensius, like many of Cicero's extant philosophical works, was known to be written as a dialogue, the Protrepticus was probably one too.
[4] Alexander states that the work further investigates the nature of philosophical contemplation and argues that this is also the proper exercise of human beings.
[4] Aristotle's protrepticus is likely the origin of the English word Protreptics, which means, “turning or converting someone to a specific end” used in a philosophical sense,[5] a word hardly ever used except in specialized philosophical treatises.
[6] Large fragments of the Protrepticus are quoted by Iamblichus in the second book of his work On Pythagoreanism.