In April 1623 he married Alida Grasvinkel. About this time a Dutchman was seized at Lillo, with letters from William Grotius to his brother. It was expected that something would be found in them against the State, and they talked of nothing less than imprisoning him; but notwithstanding the malice of his enemies, they could not find the least pretext from these letters to trouble him. In the mean time William followed the profession of an Advocate with much success: Grotius compliments him on it in a letter of the 28th of November, 1625, in which he tells him, that the life he led in shining at the bar was much more agreeable than that which is spent in public employments. William Grotius wrote about this time the lives of the Advocates, under the title of _Vitae Jurisconsultorum quorum in Pandectis exstant nomina, conscriptae a Gulielmo Grotio Jurisconsulto Delphensi_. He sent this book to his brother, who writes to him that he read it with pleasure, and was delighted to see a work which demonstrated his brother's genius, learning, and good sense. William Grotius, whose marriage had prevented his going to France to see his brother, went thither however in 1629: he returned again to Holland. William being desirous to have his brother's picture, Hugo had the complaisance to sit for it, and send it to him. The enmity of the Magistrates was still so violent at this time, that William made a mystery of this picture; in which Grotius thought he acted very prudently. In 1638 there was a talk of making William Grotius Pensionary of Delft. The conditions on which the place was offered did not suit him, and he declined it. This refusal was approved of by Grotius; for he writes to him, March 13, 1638, "As to the place of Pensionary of our native town, the more I think of it, the happier I imagine you in having got rid of it, and in preferring honour to profit: for in these times it would have been impossible to have preserved that place and your honour." The East-India Company chose him for their Advocate in 1639. Grotius compliments his brother on it March 26, that year. "I always loved that Company, he says: I look upon it as the support of the Republic; and if I could be at present of any use to it, I would most gladly embrace the opportunity." Grotius's writings concerning Antichrist were approved of by William and their Father. However, as there was reason to apprehend that the printing of these pieces might increase the number and animosity of his enemies, Grotius proposed to his Brother not to take upon him their publication, especially as he might easily find persons that were far from a factious spirit, who would willingly undertake it: but William Grotius ran the hazard of this publication, without being frightened at the consequences.