Something in the tone and pronunciation struck Challis, and awoke a long dormant memory. The sentence spoken, suddenly conjured up a vision of the Stotts' cottage at Stoke, of the Stotts at tea, of a cradle in the shadow, and of himself, sitting in an uncomfortable armchair and swinging his stick between his knees. When the child had gone--walking deliberately, and evidently regarding the mile-and-a-half walk through the twilight wood and over the deserted Common as a trivial incident in the day's business--Challis set himself to analyse that curious association. As he strolled back across the hall to the library, he tried to reconstruct the scene of the cottage at Stoke, and to recall the outline of the conversation he had had with the Stotts. "Lewes!" he said, when he reached the room in which his secretary was working. "Lewes, this is curious," and he described the associations called up by the child's speech. "The curious thing is," he continued, "that I had gone to advise Mrs. Stott to take a cottage at Pym, because the Stoke villagers were hostile, in some way, and she did not care to take the child out in the street. It is more than probable that I used just those words, 'It is very necessary to have air,' very probable. Now, what about my memory theory? The child was only six months old at that time." Lewes appeared unconvinced. "There is nothing very unusual in the sentence," he said. "Forgive me," replied Challis, "I don't agree with you. It is not phrased as a villager would phrase it, and, as I tell you, it was not spoken with the local accent." "You may have spoken the sentence to-day," suggested Lewes. "I may, of course, though I don't remember saying anything of the sort, but that would not account for the curiously vivid association which was conjured up." Lewes pursed his lips. "No, no, no," he said. "But that is hardly ground for argument, is it?" "I suppose not," returned Challis thoughtfully; "but when you take up psychology, Lewes, I should much like you to specialise on a careful inquiry into association in connection with memory. I feel certain that if one can reproduce, as nearly as may be, any complex sensation one has experienced, no matter how long ago, one will stimulate what I may call an abnormal memory of all the associations connected with that experience. Just now I saw the interior of that room in the Stotts' cottage so clearly that I had an image of a dreadful oleograph of Disraeli hanging on the wall. But, now, I cannot for the life of me remember whether there was such an oleograph or not. I do not remember noticing it at the time." "Yes, that's very interesting," replied Lewes. "There is certainly a wide field for research in that direction." "You might throw much light on our mental processes," replied Challis.