Colbert’s fourth son, Jules-Armand (1663–1704), was supposed to succeed his father as superintendent of buildings. An extended period of apprenticeship demonstrated that he was not up to the task. He had to relinquish this position, went on to have a distinguished career in the military, and died from wounds suffered at the Battle of Blenheim.

In this autograph note, the minister alerts his 17-year-old son that Louis XIV is on his way to Versailles and admonishes him to be diligent and do his duty: “The Trianon reservoir must be completed promptly. Make sure that the king finds workers there when he returns to Versailles on Thursday.”