He was absorbed in writing the instructions for the education of the future king, Frederick William III.

The physical education of the prince was his first care.

He dwelt upon the necessity of the frequent practice of dancing, fencing, and riding, to give suppleness, grace, and a good carriage--through severe training, to make him capable of enduring all hardships.

The different branches of study next occupied the king.

"It is not sufficient," he wrote, "that the prince should learn the dates of history, to repeat them like a parrot; but he must understand how to compare the events of ancient times with the modern, and discover the causes which produced revolutions, and show that, generally, in the world, virtue is rewarded and vice punished.