December, 1660.
Although I am much embarrassed, I can no longer defer rendering you a thousand thanks for having procured me the acquaintance of M. Menjot; for it is doubtless to you, Madame, that I owe it; and as I esteemed him highly already from the things which my sister had told me of him, I cannot tell you with how much joy I have received the favor which he has wished to render me. It is only necessary to read his letter to see how much intellect and judgment he possesses; and although I may not be capable of understanding the depth of the matters which he treats in his book, I will tell you, nevertheless, Madame, that I have learned much from the manner in which he reconciles in a few words the immateriality of the soul with the power of matter to change its functions and to cause delirium. I am very impatient to have the honor to converse with you on it.