1.

It is very wonderful how completely I was taken by surprise, when, on searching to discover which of your letters still remained unanswered, I found only one which held me as your debtor,--that, namely, in which you request me to tell you how far in this my leisure, which you suppose to be great, and which you desire to share with me, I am making progress in learning to discriminate those things in nature with which the senses are conversant, from those about which the understanding is employed. But I suppose it is not unknown to you, that if one becomes more and more fully imbued with false opinions, the more fully and intimately one exercises himself in them, the corresponding effect is still more easily produced in the mind by contact with truth. Nevertheless my progress, like our physical development, is so gradual, that it is difficult to define its steps distinctly, just as though there is a very great difference between a boy and a young man, no one, if daily questioned from his boyhood onward, could at any one date say that now he was no more a boy, but a young man.