I am currently reading Grotius' De iure belli ac pacis (On the law of war and peace, 1625) in the French translation by Paul-Louis-Ernest Pradier-Fodéré (Le droit de la guerre et de la paix, 1865).
At some point, this author says that the full real name of Grotius is Hugues de GROOT (in French), or Huig de Groot (in Dutch, according to Wikipedia).
However, it is never said why this man was called "Grotius". How and why did "Huig de Groot" became "Grotius"?