Re­nais­sance facts

Genitals were hidden. It took Michaelangelo seven years to complete the fresco on the altar wall of the Sistine Chapel. Once completed, the depiction of Christ and the Virgin Mary naked was considered sacrilegious, and some cardinals campaigned to have the fresco removed or censored, but the Pope resisted. Eventually, it was decided to obscure the genitals.

Giotto. It has been said that Giotto was the first real painter, like Adam was the first man. Living in the late Middle Ages (died 1337), he broke with the prevalent Byzantine style and introduced the technique of drawing accurately from life.

By mirror writing. Leonardo's writings are mostly in mirror-image cursive. The reason may have been more a practical expediency than for reasons of secrecy as is often suggested. Since Leonardo wrote with his left hand, it is probable that it was easier for him to write from right to left.