To Joshua F. Speed 
Feeling, as you know I do, the deepest solicitude for the success of the enterprize you are engaged in, I adopt this as the last method I can invent to aid you, in case (which God forbid) you shall need any aid. I do not place what I am going to say on paper, because I can say it any better in that way than I could by word of mouth; but because, were I to say it orrally, before we part,  most likely you would forget it at the verry time when it might → do you some good. As I think it reasonable that you will feel verry badly some time between this and the final consummation of your purpose, it is intended that you shall read this just at such a time.
Why I say it is reasonable that you will feel verry badly yet, is, because of three special causes, added to the general one which I shall mention.
The general cause is, that you are naturally of a nervous temperament; and this I say from what I have seen of you personally, and what you have told me concerning your mother at various times, and concerning your brother William at the time his wife died.
The first special cause is, your exposure to bad weather on your journey, which my experience clearly proves to be verry severe on defective nerves.
The second is, the absence of all business and conversation of friends, which ← might → divert your mind, and give it occasional rest from that intensity of thought, which will some times wear the sweetest idea thread-bare and turn it to the bitterness of death.
The third is, the rapid and near approach of that crisis on which all your thoughts and feelings concentrate.
If from all these causes you shall escape and go through triumphantly, without another ``twinge of the soul,'' I shall be most happily, but most egregiously deceived.
If, on the contrary, you shall, as I expect you will at some time, be agonized and distressed, let me, who have some reason to speak with judgement on such a subject, beseech you, to ascribe it to the causes I have mentioned; and not to some false and ruinous suggestion of the Devil.
``But'' you will say ``do not your causes apply to every one engaged in a like undertaking?''
By no means. The particular causes, to a greater or less extent, perhaps do apply in all cases; but the general one, nervous debility, which is the key and conductor of all the particular ones, and withoutPage 266 which they would be utterly harmless, though it does pertain to you, does not pertain to one in a thousand. It is out of this, that the painful difference between you and the mass of the world springs.
I know what the painful point with you is, at all times when you are unhappy. It is an apprehension that you do not love her as you should. What nonsense!---How came you to court her? Was it because you thought she desired it; and that you had given her reason to expect it? If it was for that, why did not the same reason make you court Ann Todd,  and at least twenty others of whom you can think, & to whom it would apply with greater force than to her? Did you court her for her wealth? Why, you knew she had none. But you say you reasoned yourself into it. What do you mean by that? Was it not, that you found yourself unable to reason yourself out of it? Did you not think, and partly form the purpose, of courting her the first time you ever saw or heard of her? What had reason to do with it, at that early stage? There was nothing at that time for reason to work upon. Whether she was moral, aimiable, sensible, or even of good character, you did not, nor could not then know; except perhaps you ← might infer the last from the company you found her in. All you then did or could know of her, was her personal appearance and deportment; and these, if they impress at all, impress the heart and not the head.
Say candidly, were not those heavenly black eyes, the whole basis of all your easily reasoning on the subject?
After you and I had once been at her residence, did you not go and take me all the way to Lexington and back, for no other purpose but to get to see her again, on our return, [in that] seeming to take a trip for that express object?
What earthly consideration would you take to find her scouting and despising you, and giving herself up to another? But of this you have no apprehension; and therefore you can not bring it home to your feelings.
I shall be so anxious about you, that I want you to write me every mail. Your friend LINCOLN
 ALS, IHi.
 Speed had returned to Springfield with Lincoln in September, 1841, but was now returning to Kentucky to live and to marry Miss Fanny Henning. The date given to this letter by Nicolay and Hay has been followed as presumably the date assigned to it by Speed for the Complete Works, but Speed wrote Herndon, September 17, 1866, that he remained in Springfield until the ``1st of Jany. 1842'' (DLC-HW). In any event, Lincoln wrote the letter before Speed's departure and presumably gave it to him before he left. There is no postmark to indicate that the letter went through the mail.
 Younger sister of Mary Todd.