Next, from what has been said it is plain, that such a process of reasoning is more or less implicit, and without the direct and full advertence of the mind exercising it. As by the use of our eyesight we recognize two brothers, yet without being able to express what it is by which we distinguish them; as at first sight we perhaps confuse them together, but, on better knowledge, we see no likeness between them at all; as it requires an artist’s eye to determine what lines and shades make a countenance look young or old, amiable, thoughtful, angry or conceited, the principle of discrimination being in each case real, but implicit;—so is the mind unequal to a complete analysis of the motives which carry it on to a particular conclusion, and is swayed and determined by a body of proof, which it recognizes only as a body, and not in its constituent parts. And thirdly, it is plain, that, in this investigation of the method of concrete inference, we have not advanced one step towards depriving inference of its conditional character; for it is still as dependent on premisses, as it is in its elementary idea. On the contrary, we have rather added to the obscurity of the problem; for a syllogism is at least a demonstration, when the premisses are granted, but a cumulation of probabilities, over and above their implicit character, will vary both in their number and their separate estimated value, according to the particular intellect which is employed upon it. It follows that what to one intellect is a proof is not so to another, and that the certainty of a proposition does properly consist in the certitude of the mind which contemplates it. And this of course may be said without prejudice to the objective truth or falsehood of propositions, since it does not follow that these propositions on the one hand are not true, and based on right reason, and those on the other not false, and based on false reason, because not all men discriminate them in the same way. Having thus explained the view which I would take of reasoning in the concrete, viz. that, from the nature of the case, and from the constitution of the human mind, certitude is the result of arguments which, taken in the letter, and not in their full implicit sense, are but probabilities, I proceed to dwell on some instances and circumstances of a phenomenon which seems to me as undeniable as to many it may be perplexing. 1. Let us take three instances belonging respectively to the present, the past, and the future.