optical illusions 1

When the Greeks built their buildings (especially temples), they also sometimes incorporated a number of small refinements to make the building more beautiful:

* although the columns become thinner towards the top, they bulge in the middle; if they didn't do that, they would look thinner in the middle � by making the columns bulge slightly, the Greeks actually made them look straight
* similarly, the gaps between the columns on the corners of a temple and the next columns is slightly less than the gaps between other columns; this stops the corner columns looking so isolated � it also looks better because it allows the architect to put a triglyph at the corner without the column sticking out further
* the corner columns are slightly thicker than the other columns, because they are viewed against the bright sky rather than the darker walls of the building, and this makes them look slightly thinner than they really are
* on some Greek temples, all of the surfaces lean inwards, so that if you kept building all of the columns up to a great height they would meet like a Pyramid (the corner columns of the Parthenon would meet 2.25 km up in the sky)
* the horizontal lines of the temple also sometimes rise slightly in the middle and gently slope downwards towards the corners

All of these refinements, in fact, make the building look as if there are only straight lines, but they also seem more pleasing to the eye. There are several different theories about what makes them more pleasing � some people think that it makes the building seem heavier, like the columns are bulging under the strain; some people think that it directs the eyes upwards and emphasises the height of the building; some people think that the eye is expecting straight lines and is surprised and more interested by the curves. Nobody is quite sure what motivated the Greeks, but it seems to have worked.