When the hour approached for Michelangelo's departure, the Duke jestingly said to him: 'You are my prisoner now.

If you want me to let you go free, I require that you shall promise to make me something with your own hand, according to your will and fancy, be it sculpture or painting.' Michelangelo agreed; and when he arrived at Florence, albeit he was overwhelmed with work for the defences, he began a large piece for a saloon, representing the congress of the swan with Leda.

The breaking of the egg was also introduced, from which sprang Castor and Pollux, according to the ancient fable.

The Duke heard of this; and on the return of the Medici, he feared that he might lose so great a treasure in the popular disturbance which ensued.

Accordingly he despatched one of his gentlemen, who found Michelangelo at home, and viewed the picture.