Our cherished friend Liberty reveals herself as a naked lie

In the 1960s and 1970s, it was possible to buy soft-porn postcards of a girl clad in a bikini or wearing a dress; but when you moved the postcard a little bit or looked at it from a slightly different perspective, the dress magically disappeared and you could see the girl’s naked body. This is parallax at its purest: the apparent change in an object caused by a shift in the observational position that allows[ …]