In 1844 Wilhelm K. von Haidinger published a paper in Poggendorfs Annalen as to how to see the polarization of light. It appears as what is known as Haidinger's Brush and there is a graphic at Wikipedia. I've found the graphic is not quite accurate though. The yellow part looks like a sheaf of wheat tied at the middle, with the inividual stalks hanging out, and is shaped like an hourglass. That is, it looks like a double brush. There are (at least) two ways to learn to see the brush. The natural style is at twilight to look at a cloudless portion of sky 90 degrees away from the Sun. I found that the trick is to NOT stare at one point. It is better to shift the gaze rapidly. If you are not concerned with being thought a lunatic spinning around is even better. The yellow portion will point at the Sun. The modern style is to gaze at an LCD and tilt one's head back and forth. In the screen here before me the brush appears either vertically or horizontally, depending on whether my head is tilted left or right. In 1954 a William Shurcliff learned to distinguish left and right circular polarization in that the axes of the brush become skewed. Polarization is a quantum spin phenomenon, so in this case it is possible to see quantum spin. I never imagined neither did I dream of such a thing, but there it is.