Grotius had three sons and three daughters by his marriage. His eldest son, Cornelius, studied in Holland under the direction of his grandfather[736]. Grotius sent for him afterwards to Paris, where he himself superintended his studies. He wrote to his brother, William Grotius[737], Aug. 16, 1630, that Cornelius had learned the Hebrew grammar; that he was studying the Greek and Logic; and had made himself matter of the Art of Oratory, without neglecting Poetry, for which the young Cornelius had a particular turn. Some very good verses, written by him, are published in the poems of Vincent Fabricius. Grotius made him read Vossius's pieces on rhetoric, which he thought could not be excelled; he afterwards wanted Cornelius to study the Roman Law, and the Laws of Holland: he also made him read Physics and Metaphysics; but his progress in these sciences was inconsiderable, according to Du Maurier, on account of his indolence and love of pleasure. Grotius sent him after this to make his court to the High Chancellor, who passed the beginning of the year 1636 at Straelsund: Oxenstiern received him very graciously, and took him into his service as Latin Secretary[738]. Grotius was at the height of his joy on seeing his son in a capacity of meriting the esteem and protection of such a great man as Oxenstiern: he flattered himself[739], that the honourable place, which his son held, would induce him to shake off his indolence; and he made him frequent remonstrances on this subject: but Cornelius's natural temper prevailed, and he considered his employment as attended with too much trouble. He imagined that a military life would suit him better[740], and wrote to his father on that head. Grotius opposed this new turn for some time; but his remonstrances producing no effect, he wrote to Muller[741], April 4, 1638, that his son had preferred Mars to the Muses, and that he had thought fit to yield to his choice, as war was also a road to glory; and moreover the time, which Cornelius had spent in literature, would not be absolutely lost for war. He added, that the Duke of Weymar being the greatest and most experienced general of his age, he was very desirous that his son should serve under such an able master; and that he would send him with a reinforcement that was marching to that Prince, who, he hoped, would assist him with his advice. Cornelius was very well received by the Duke[742]; and for some time kept up an exact correspondence with his father by letters, who complimented him on his diligence in writing. The Duke of Weymar promised to advance him, if he paid a proper regard to his father's counsels. Cornelius was by nature so inconstant, that he soon took a dislike to the army: he had even thoughts of returning to his father, who diverted him from it as a step which would dishonour him.