Concept

Gnomon

Overview

A gnomon (; from Ancient Greek γνώμων (gnṓmōn) 'one that knows or examines') is the part of a sundial that casts a shadow. The term is used for a variety of purposes in mathematics and other fields, typically to measure directions, position, or time.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

Possible passages

Found by search and not yet checked by a person; they may only mention the idea in passing.

From the use of the gnomon there naturally grew up the conception of angular measurements; and with the advance of geometrical conceptions there came the hemisphere of Berosus, the equinoctial armil, the solstitial armil, and the quadrant of Ptolemy--all of them employing shadows as indices of the sun's position, but in combination with angular divisions. It is obviously out of the question for us here to trace…
Herbert Spencer, Essays on education and kindred subjects
Opens on Gnomon; names Gnomon.
Read the chapter · Open in the reader
Here again it is observable, not only that the instrument is found ready made, but that Nature is perpetually performing the process of measurement. Any fixed, erect object--a column, a dead palm, a pole, the angle of a building--serves for a gnomon; and it needs but to notice the changing position of the shadow it daily throws, to make the first step in geometrical astronomy. How small this first step was, may be…
Herbert Spencer, Illustrations of Universal Progress
Names Gnomon several times.
Read the chapter · Open in the reader
But there are some things which undergo increase but yet not alteration. The square, for instance, if a gnomon is applied to it, undergoes increase but not alteration, and so it is with all other figures of this sort. Alteration and increase, therefore, are distinct.
Aristotle, The Categories
States what Gnomon is; names Gnomon.
Read the chapter · Open in the reader

Gnomon

Overview

Possible passages

Philosophers who discussed Gnomon

Related ideas

Place in the tradition