Then came the portrait, which, the instant I looked at it, startled me strangely. The face as I saw it there was unknown to me; but that somewhere and sometime in my life I had seen the face--not of some one resembling this man, but of the very man himself--I was positive, though under what circumstances I could not, for the life of me, remember. I have as a rule an excellent memory, and I attribute this very largely to the fact that I _never allow myself to forget_. Memory, like the lamp which came into the possession of Aladdin, can summon magicians to aid us at call. But memory is a lamp which must be kept bright by constant usage, or it ceases to retain its power. The slave-sprites serve mortals none too willingly, and if, when you rub the lamp, the attendant sprite come not readily to your call, and you, through indolence, allow him to slip back into the blue, be sure that when next you seek his offices he will again be mutinous. And if on that occasion you compel him not, he will become more and ever more slack in his service, and finally will shake off his allegiance and cease to do your bidding at all. Hence, as I have said, I never _allow myself to forget_, though when I stumble upon a stubborn matter I go like a dog with a thorn in his foot till the thing be found. Such a matter was it to remember where and when I had seen the face that so reminded me of Captain Shannon. Day after day went by, and yet, cudgel my brains as I would, I could get no nearer to tracing the connection, and but for sheer obstinacy had pitched the whole concern out of my mind and gone about my business. Sometimes I was nigh persuaded that the thing I sought was sentient and alive, and was dodging me of pure devilry and set purpose. Once it tweaked me, as it were, by the ear, as if to whisper therein the words I was wanting, but when I turned to attend it, lo! it was gone at a bound and was making mouths at me round a corner. It seemed as if--as sportsmen tell us of the fox--the creature rather enjoyed being hunted than otherwise, and entered into the sport with as much zest as the sportsman. Sometimes it cast in my way a colour, a sound, or an odour (I noticed that when I smelt tobacco I seemed, as the children say, to be getting “warmer”) which set me off again in wild pursuit and with some promise of success. And then when I had for the fiftieth time abandoned the profitless chase, and, so to speak, returned home and shut myself up within my own walls, it doubled back to give a runaway knock at my door, only to mock me when I rushed out by the flutter of a garment in the act of vanishing. But I was resolved that not all its freaks should avail it ultimately to escape me, for though I had to hunt it through every by-way and convolution of my brain, I was determined to give myself no rest till I had laid it by the heels,--and lay it by the heels I eventually did, as you shall shortly hear.