In 1598 he was appointed to accompany a special Embassy which was being sent by the Netherlands to the King of France, Henry IV. His reputation had gone before him. The men of the day crowded to see him, and the King received him and with his own hand hung his portrait round the youth’s neck. So much flattery might easily have turned his head, but he already showed a calm judgment and the wisdom of a man of long experience. He did not loiter in this pleasant atmosphere, but returned to his work in Holland. But there was another danger before him. He might have buried himself in his studies, and, like other learned men of his time, and, indeed, of all times, accumulated a lot of useless knowledge. So many great scholars have become experts in some particular subject, and have shut themselves off from contact with their fellow-men. Their mind becomes their idol, and they fail to see that mere brain-power is of little service if it is not used for some great purpose, and if it is not inspired by moral and humane sentiments. Grotius avoided this course; he was anxious for active life, and wanted to join in and help his country and humanity in some practical way. He had avoided becoming a prig, a prodigy, or a bookworm, and when he took up the career of a lawyer he also avoided using his rapid promotion for the purpose of money-making and personal success. His extraordinary talents were like the spreading sails of a ship. They might have capsized him if he had not had plenty of ballast.
How little he thought of fame and applause, and how he worked for true knowledge and in order to prepare himself for the future, is shown by the discovery at The Hague, two hundred years later, of a manuscript of a big book written by him when he was twenty-two, but never published. One of the chapters of this book he issued as a treatise under the title of “Mare Liberum.” It was an argument against the claim made by some nations, specially Portugal at this time, that the seas could be owned by a nation, and that no other nation could fish in them or navigate them without her permission. Grotius maintained the freedom of the seas was necessary to enable nations to communicate with one another, and it could not be taken away by any power whatever. James I very much disapproved of this book, as he thought it interfered with the rights of Great Britain. He ordered his Ambassador in Holland to take measures against the author. But as nothing could be done, the King instructed the great English lawyer, John Selden, to write a reply, which he did in a learned book called “Mare Clausum.” But Grotius really had the best of the argument, and his view was eventually adopted.