What goes betwen your mascara and your eyeshadow, if you have a predilection for such adornments. I'm the sort of person who does (no, I will never be an androgynous geek girl). This is why:

The eyes are the windows to the soul. It's a truism. The ripples of muscular adjustments that result from the most subtle motion of the eye tell more secrets than other body language. Looking someone straight in the eyes in good lighting is seeing everything they are. We judge others based on our visual impressions. I want to control that assessment. Eyeliner has the effect of making the eye appear half closed. Like open blinds on a window, it shows the same thing, but alters it just a little so that you can never feel you're getting a clear idea of what lies behind.

Then there's the other half, which is more general. It's a habit. I've worn eyeliner for such a long time that I don't feel like myself without it. I don't dislike my natural appearance - I've been told I look better without it. But my mental image of myself includes eyeliner. It represents things about me that I am proud of, the above being only a part of that. I am not a boy, but neither am I the sort to spend half an hour putting on makeup with the intended effect of looking natural. It's art - creating two perfectly symmetrical swipes, and leaving the rest a blank canvas, blemishes and freckles and all. It's a whisper of glamour, an inkling of pretense, amidst the glaring mistakes and sublime beauties of genetics. It's a ritual. It's wonderful in its vain futility.