Mr.Barbeyrac possessed all the necessary qualifications for executing properly such a difficult translation as that of the treatise _Of the rights of war and peace_.
This so excellent and highly esteemed work was however severely criticised by one of the most learned men of the last century.
Salmasius, who had been Grotius's admirer, and who in the latter part of his life did all he could to destroy his reputation, never spoke of _The rights of war and peace_ but with the greatest contempt: which was the more shocking; as, in his dispute with the English on the right of Kings, he every where copies Grotius, and when he departs from him is sure to blunder: with which Boeclerus has justly reproached him.
We cannot deny Salmasius profound learning; but he was a man swayed by his humour, often judged from passion and jealousy, had too high an opinion of himself and too much contempt for others, and in fine found fault with whatever was not his own thought, as the learned Gronovius remarks.
He ventured to advance, some time after Grotius's death, that a professor of Helmsted had undertaken to prove that every page of Grotius's book contained gross blunders; and he speaks it in such a manner as gives room to think he was of the same opinion.

This Professor was called John de Felde; he published his notes against Grotius in 1653.

Had the great Salmasius been still alive, I believe, says M.
Barbeyrac, that with all his secret jealousy against the author censured, he would have found himself greatly disappointed in his expectations from John De Felde's project: never was any thing so wretched.

One would be surprised a Mathematician could reason so ill, did not other much more signal examples clearly demonstrate that the knowledge of the Mathematics does not always produce justness of thought in matters foreign to that science.

We find here a man who seeks only for censure, and knows not what he would have: he fights with his own shadow, and for the most part does not understand the thoughts of the author he attacks; and when he does understand them draws the most groundless consequences that ever were heard of.