That his stupidity was not blameworthy is shown by the sympathy of Isaac’s superiors; that it was not natural is known to our readers by their acquaintance with his native ability exhibited in his journals and letters.  The difficulty was confined almost wholly to study; to fix his attention on the matter in the text-books, or to grasp it and hold it in memory, was beyond his power.  Meantime his letters to his friends in New York and elsewhere were full of life.  He kept a copy of a carefully written one, addressed to an old-time friend of the Brook Farm community.  It is a model of brief statement of great truths, and proves that the social difficulty can only be fully remedied by the Catholic Church, which has an elevating force incomparably more powerful than any other known to humanity.  The method used and the choice of arguments are peculiarly Isaac Hecker’s own, and the tone, though affectionate, is one of authority, as that of an exponent of evident truth.  His letters to his mother and his brothers are full of controversy, abounding in appeals to Scripture, to the voice of conscience, to the dictates of reason; and although the tone is one of deep affection, the attacks on Protestantism are keen, and the use of facts and persons as illustrations full of intelligence.  Most of the letters which we have found were addressed to his mother, for whose conversion he had an ardent longing.  With one of them he sends her a little manuscript treatise on true Bible Christianity which he had himself prepared.  We give the reader extracts from two letters, the first from one to his brother John and the second from one to his mother: 

“Your lamentation, dear John, on my separation from you, excites in me a great astonishment.  To justify this separation it seems to me that you have only to open a page of the Gospels of Christ, and to read it with a sincere belief in the words and a generous love of the Saviour.  As for me, I regret nothing so much as that I have not a thousand lives to sacrifice to His service and love.  Yes, I love you all more than I ever did, and I would count nothing as a cost for your present and eternal good.  Yet, by the grace of God, I love my Saviour infinitely, infinitely, infinitely more.  Alas! when will those who profess to be Christians learn the significance of Christ’s Gospels and His blessed example.  I am not ignorant nor insensible of the love we owe to our parents and relatives—­no, I am not insensible of this love; but in me it is all in Christ, as I would wish yours were. . . .  I embrace you, dear brother, in the love of our crucified Lord.”