The sun is many times the size of the earth, which resembles, comparatively speaking, but a small splotch upon its surface, so that the shadow cast by the opaque matter of the earth intercepting the sun's rays, necessarily diminishes in width until it disappears in a point of space, making a cone-shaped shadow, resembling a "dunce cap," with its base resting upon the earth. This shadow, more or less relieved in intensity, from time to time, by the sun's rays reflected back upon the earth from the moon outside the shadow, is called "night."
"Night," for any particular person, is the period of time it takes for a point on the earth's surface, occupied by him or her, rotating with the earth upon its axis, to pass through the earth's own shadow. This period varies in the exact time of its commencement and termination with every meridian of longitude, so that a given "night" just commenced in San Francisco is well toward termination in London or Paris; and its duration at every point is determined by the location of that point north or south of the equator, so that it is longer or shorter with every parallel of latitude.
The material mind has seized upon this circumstance of the earth shadow to give itself a measured sense of existence, measured by the shadow of the earth itself, the turning whereof upon its axis gives this mind its sense of day and night, which are terms of its own conception to denote the sun's light and the earth's shadow, and also to denote this material mind's own notion of the passing of time.
