The speaker tries to describe how well he knew a woman, and every comparison undercuts itself. Each one suggests knowledge that is partial, awkward, or gained only indirectly. A lake sees a mountain only as a reflection, upside down and broken up by every breeze, so it has to put the image back together again and again. A clown knows boredom well, yet the speaker claims to know her better than he knows his own absurdity, which is a funny and slightly sad thing to admit.
The ear candle is the oddest image. It promises intimacy but delivers "failure," and the line about flattery makes the closeness feel fake or clumsy. The final image is the most telling: night knows lightning only through the gaps, the dark moments between flashes. That suggests the speaker understands her mostly by what he missed or lost. The mood is wry and tender, with a note of regret under the jokes. The humor keeps the feeling at arm's length, but it never quite hides it.