Final answer:
French theatrical conventions drew significantly from Italian neoclassical principles, with influences merging large casts and complex plots, similar to those in England and Spain. The French Academy solidified these conventions, which were further propagated under King Louis XIV's patronage.
Step-by-step explanation:
Many of the French theatrical conventions were adopted from Italian influences, particularly during the 17th and 18th centuries. The neoclassical movement in Italy, which emphasized specific structural and thematic elements for theatre, heavily inspired the French theatrical landscape. Neoclassical theatre prioritized perspective, visual balance, and followed the tenets of verisimilitude, decorum, clear structural divisions such as the five-act play, and a didactic purpose.
In the realm of playwrights such as Pierre Corneille, the French Academy was established under Cardinal Richelieu's direction. Here, French adaptation of the neoclassical standards was further refined. For instance, Corneille's famous play Le Cid used a Spanish original, which he adapted to meet the neoclassical criteria, although not without critique for certain perceived transgressions against these new standards.
The patronage of King Louis XIV also played a critical role, promoting theatre that incorporated Italian and Spanish elements, including neoclassical ideals and Italian proscenium arch theatre design. Additionally, large casts and complex plots were common as in English and Spanish theatre. Molière, another key French playwright, managed to blend neoclassical conventions with the unique elements of French farce and commedia dell'arte, creating original and popular French comedies.