For some time he entertained hopes that Cardinal Richelieu would favour
him: Jan. 19, 1641, he writes thus to his brother[664]: "When my book is
published, many Protestants will see that the reconciliation of the
Churches is easier than they imagined: for the principal basis of the
Reformation may subsist with the Pope's consent, provided the affair be
managed with mildness and without giving him offence. I write this on
good grounds: Cardinal Richelieu thinks the thing will succeed: he has
said so to several."

Grotius had either been misinformed, or the Cardinal changed his
language: for the former writes to his brother[665], March 24, 1642, "As
Cardinal Richelieu speaks differently from what he did some time ago
about the peace of the churches, I am afraid this change conceals some
ill design against the Reformed."

Grotius, finding at length that the project of a coalition was
impracticable without the approbation of the Catholics, contracted an
intimacy with Father Petau, to whom he communicated all his works
relating to religion and the reconciliation of the churches. In a letter
of the 3d of December, 1640, he desires him to send him his remarks on
his works, "That, says he, by your assistance I may add, suppress, or
correct, as shall be most necessary for promoting truth and peace. Would
to God that I had as much genius and learning as some others: I would
accomplish what it is great barely to attempt."

He communicated to Father Petau the manuscript of his answer to
Rivetus[666], desiring him to point out what was not agreeable to truth,
or had not a tendency to promote peace. "I am resolved, says he, to
publish my answer as soon as I have your opinion, to which I pay great
regard."

Father Petau gives us the history of his acquaintance with Grotius, in
his XIIth letter[667]. "I had, says he, a great desire to see and
converse with him; we have been long together, and very intimate. He is,
as far as I can judge, a good man, and of great candour. I do not think
him far from becoming a Catholic, after, the example of Holstenius, as
you hoped: I shall neglect nothing in my power to reconcile him to
Christ, and put him in the way of salvation."

Father Petau mentions him again in another letter, written to Cardinal
Francis Barberinus[668]. His Eminence had applied to that learned Jesuit
for information in what state Grotius had left, at his death, his work
on the Antiquities of Sweden. Father Petau makes him