Answer: Baldassare Castiglione.
Explanation: Baldassare Castiglione, Count of Novilara was an Italian courtier, diplomat and author, best-known for his study of the ideal courtly life, "Il Libro del Cortegiano".
"Il Libro del Cortegiano" or "The Book of The Courtier" provides a fascinating insight into Renaissance court life, and was the ultimate ‘how to’ guide for aspiring courtiers.