Mathematical Plato by Roger Sworder

Author:Roger Sworder [Sworder, Roger]
Language: eng
Format: epub
Tags: Philosophy, History & Surveys, Ancient & Classical
ISBN: 9781597311380
Google: 4dmLmwEACAAJ
Amazon: 1597311383
Publisher: Angelico Press
Published: 2013-08-14T22:00:00+00:00

Imagine you are standing at some point on the Equator. The Sun will be directly overhead this point at midday at the Equinoxes.

Imagine, too, that you are looking West to the Western horizon, and that you have carefully marked in times past the most southerly point just touched by the Sun’s orb as it sinks below the horizon at the Southern Solstice. You have also marked the most northerly point at the Northern Solstice, and the point where the centre of the Sun’s orb sinks below the horizon at the Equinoxes. Imagine now that these three points mark the threshold of a great doorway reaching up to Heaven. Beginning from the furthest point South touched by the Sun, draw a line straight up into the sky. This line is the southern doorpost of the doorway. From the farthest point North do the same to make the northern doorpost. The threshold of the doorway is the section of the Western horizon between the terrestrial Tropics; and the lintel overhead is the corresponding arc of the celestial meridian between the celestial Tropics.

Imagine now that this doorway in the Western sky is filled by a pair of great doors, as high as the Heaven. The door on the left has as its doorpost the line drawn straight up from the southernmost point. The door on the right hangs from an equivalent post in the North. The junction formed when the two doors are closed together is the line from the terrestrial Equator to the celestial Equator. We may imagine that during the six months the Sun is south of the Equator, the door on the left is open. During the six months the Sun is north of the Equator, the door on the right is open. At the Equinoxes both doors are open. Or perhaps they are both shut then and through the tiny aperture between them the Sun passes.

We have imagined the doorway as based on the section of the

Western horizon between the extreme points of the Sun’s southerly and northerly courses. These points are determined by the eye alone. The same is true of the Sun’s risings over the Eastern horizon.

At sunset and sunrise we can mark most easily the Sun’s courses against the earth. But the doorway we have constructed with its doors may be said to stand at every point along the Sun’s journey, though the exact location of its doorposts and doors are indeterminable by the eye except at setting and rising. On every meridian, 62

The Nuptial Number

on every line of longitude drawn round the globe through the poles, we may theoretically mark off the section between the Tropics to serve as the threshold, and the corresponding section of the celestial line of longitude to serve as lintel. In this way we may think of the Sun as passing through the doorway at every point on its journey.

When the Sun sinks in the West, we think of it as entering through the doorway; when the Sun rises in the East, we think of it as leaving through the doorway.

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