Periodic Sentence

I'm always fascinated with the last lines of books. I find it intriguing what last words the author wanted the audience to read as a last thought, a last moment.

There, in front of us, where a broken row of houses stood between us and the harbor, and where the eye encountered all sorts of stratagems, such as pale-blue and pink underwear cakewalking on a clothesline, or a lady's bicycle and a striped cat oddly sharing a rudimentary balcony of cast iron, it was most satisfying to make out among the jumbled angles of roofs and walls, a splendid ship's funnel, showing from behind the clothesline as something in a scrambled picture - Find What the Sailor Has Hidden - that the finder cannot unsee once it has been seen.

Even though this is all one complete sentence, what struck me was the last bit about "something in a scrambled picture... that the finder cannot unsee once it has been seen." I remember seeing a lot of "I Spy" pictures when I was younger, or those images where you stare at it enough and see an image that appears to be popping out. You would struggle to see it, and then all of a sudden it came to you, and you were so proud of yourself. The next time you looked at that picture, you'd see the image or find the object right away. It felt like you couldn't even trick yourself to work at it like you once did. I don't know about other people, but I always felt sort of lost when I knew exactly where Waldo was in all of my books. What an interesting last image for Nabokov.