In several of his letters he clears himself from the charge of Socinianism in such a manner as leaves us no room to doubt his regarding it as a very dangerous heresy. "I give myself little trouble, he writes to his brother[688], June 4, 1639, about the calumnies spread against me by the worst of men, in relation to Socinianism. They may be easily confuted before equitable judges by the writings which I have already published, and by those I shall yet publish. I have defended the sentiments of the ancient Church concerning the Trinity, Christ's satisfaction, and future punishments, by Scripture and the consent of antiquity; and have confuted the contrary opinions. Calvin might more justly be[689] accused of Arianism, than I of Socinianism." Sorbiere, who had been his Secretary; discovering a great propensity to some opinions of Socinus, Grotius earnestly admonished him[690] to abstain from such dangerous innovation. One of the principal grounds on which they went, was, as we have already seen, his silence concerning the Trinity, in his book _Of the truth of the Christian religion_: but he has justified his method in such a manner, that this objection cannot be sustained by an equitable judge: he seems to have foreseen it; for, writing to his brother from his prison at Louvestein whilst he was composing this treatise in Dutch verse, "My intention, he says, is not to explain the doctrines of Christianity, but to make the profane, the Pagans, Jews, and Mahometans acknowledge the truth of the Christian religion, and afterwards have recourse to our sacred books to be informed of its tenets. The Trinity, and Christ's divinity could not be introduced into my arguments; for these doctrines will never bring over unbelievers to the Christian faith, and those who attempt to demonstrate them by other arguments than such as are drawn from scripture, absolutely lose their labour: but the authority of the scriptures being once established, these doctrines ought to be held proved." He omitted therefore all mention of these points, not because he disbelieved them, but because he judged it more proper to prove first the divinity of the sacred books, and the mission of Christ: and, as we have already observed, the same method has been followed by the most successful writers on the Truth of Christianity.