The age of Pericles has been known through the centuries as the “Golden Age of Greece,” but the judgment of time has forced us to the conclusion that it was also the golden age of the world as far as the beauty of architecture and sculptural art is concerned. There is no more intriguing part of the whole narrative of the Parthenon than this story of the subtlety of the Greeks in overcoming optical illusions and neutralizing differences in distance. Perhaps the most important, certainly the most prominent, of the refinements of the Parthenon is the curvature of the horizontal lines. It is not true, as some textbooks have it, that there is no straight line in the Parthenon. There are a number of them, but all of these straight lines are vertical. What should be said is that there are no straight horizontal lines in the Parthenon. Another refinement used by the Greeks in adding to the beauty of the Parthenon relates to the columns. The visitor is certain to be impressed by the softness of the Doric columns. This is especially true of those of the Naos where their proximity to each other emphasizes their beauty as they are caught banked against each other. When thus seen all other columns fail by comparison and seem as stiff as pokers. This quality of softness is given them by the fact that all columns, both in the Naos and on the exterior of the building, are different in diameter from those beside them and all are also spaced differently. Still another refinement pertaining to the columns is technically known as entasis, which is that quality which gives to them their beautiful symmetry. In discussing the columns in relation to their softness it was suggested that they be seen banked against each other. In the discovery of their symmetrical beauty, however, they should be seen singly. The column apparently rises from the floor at its largest diameter and gradually diminishes in a beautifully fluted shaft, having the very breath of symmetry in every line to the top. That is the way it appears; but, as a matter of fact, if the column had been constructed as it actually looks, then, instead of seeming beautifully symmetrical, because of an optical illusion, it would have appeared concave at a point just below the center of the column. Knowing this from experience, the Greeks filled in just enough to correct the results of the optical illusion and the column in reality is bulged near the center.