Sprezzatura: 'a certain nonchalance, or as a so called effortless grace so as to conceal all art and make whatever one does or says appear without effort and almost without any thought about it'.
The Italian word sprezzatura originates from Il Cortegiano (The Book of the Courtier) by Baldassare Castiglione. The book describes the perfect courtier, and this appearance of effortless and ease was, in Castiglione's opinion, a vital trait to possess.
