Da Vinci Was a Bastard [Do not] make figures too gnarled with muscles, lest they resemble a sack of walnuts. —Leonardo da Vinci, on Michelangelo   A hardly-mentioned talent: improvisation on the silver lyre— his playing surpassing many of the court professionals of the Duke of Milan. Six musicians entertained Mona Lisa Gherardini while he painted. (Some say her one-sided smile was a result of bruxism, the habit of grinding one’s teeth from stress; others say her face was his own.)   Left-handed, a vegetarian, illegitimate, very strong (with his bare hands, he could unbend a horseshoe).   He actively…