Instead he found an outlet in the smaller Salon de la corréspondance, where in 1782 he showed a tenebrist Piquant effect of the light of a lamp.

Two years later he was received at the Académie with a historical subject, Alexander taming Bucephalus and was made a member 3 October 1787, his second attempt, on the strength of The Death of Agis.

[2] In his best-known painting, Zeuxis choosing among the most beautiful girls of Crotona, shown at the Salon of 1791,[3] Monsiau illustrates an anecdote of the painter Zeuxis, recorded in Pliny's Natural History, that exemplifies an essential aspect of the Classical approach to artistic creation, in the artist's refining an ideal Art by selecting from among the lesser beauties of Nature.

Monsiau's great public commission was a commemoration of the occasion on 26 January 1802, at which Napoleon delivered an authoritarian constitution to the Cisalpine Republic at a convocation of notables (the consulta) at Lyon.

His portrayal of a sensational episode in which an escaped lion from the Grand Ducal menagerie in Florence had dropped a child it had picked up, without harming it, was exhibited at the Salon of 1801 and is conserved in the Louvre.