Let us begin from the beginning. I am an infant scrambling on the floor where the said inkstand is casually lying. Having a congenital impulse (commonly called “instinct”) to touch and suck anything that comes in my way, and especially anything bright, I greedily and rapidly approximate my lips to the corner of this polished object. I recoil with a sharp shock of pain. The pain abates. The instinctive recoil from the inkstand has left in me an instinctive aversion to the pain-causing object: but my touching and sucking instinct again revives, and as soon as it prevails over the recoiling instinct, I am impelled again towards the inkstand, not so rapidly as before, but still too rapidly. I recoil again, with pain lessened but still acute. I am acquiring “knowledge”: I “know,” though I cannot put it into words, that I have twice found the inkstand not-to-be-rapidly-approached-under-penalty-of-a-certain-kind-of-pain, in other words, “hard.” But I try again; I try four, five, six times: I find that when I approach with less velocity my pain is less, and when with sufficiently diminished velocity, there is no pain at all; I touch and suck in peace: but when I forget my experience and suppose that the inkstand—even though I dash wildly at it after my old fashion—will “behave differently this time,” I find that I am mistaken: the inkstand will not “behave differently”; it always behaves in the same way. By this time then I know something very important indeed. But pause now, my friend, and ask yourself how much this infant has a right to say he “knows,” so far as the evidence of the senses guides him. All that the senses have told him is that on five, six, seven, say even seventy, occasions, he found the inkstand hard. But is this all that he “knows”? You know perfectly well that he knows infinitely more: he has made a leap from the past into the future and knows that the inkstand _will_ be found hard whenever he touches it. When he grows up and attains the power of speech he will generally express his knowledge in the Present Tense: “I must not strike the inkstand with my mouth for it _is_ hard”: but in reality this “is” implies “will be”; “I must not strike the inkstand with my mouth for I _shall find_ it hard.” Now what is it that has produced in him this conviction which no philosopher can justify by mere logic, but which every baby acts on? It seems to have arisen thus. The baby has received in rapid succession two sensations, first, that of a violent approximation to the inkstand, secondly, a sudden shock of pain. Having received this pair of sensations very frequently, he cannot help associating them together in his thoughts; so that now the thought of a violent approximation to the inkstand necessarily suggests to him the thought that it is not-to-be-approached-violently, or “hard.” He began by learning to expect that perhaps, or probably, the first sensation would be followed by the second; but having found, after constant