The Essence of the Circle

Spinoza argues that the Euclidean definition of Circle, 'a set of points equidistant from a single point', expresses a property, but not the essence, of it. However, he does not further consider that the essence of the Circle does not consist in its status as a Geometric figure. No doubt, the Circle is most familiar as the latter, but it is also both a representation of Rotation and a model of the Wheel. As a representation of Rotation, it is independent of geometrical features, i. e. Circumference, Center, Diameter, etc. are all superimposed and extrinsic. As a model of the Wheel, such features are abstractions from physical parts, e. g. a circumference represents a rim, a center represents an axle, etc. Clearly, this two-fold abstractness of the Circle does not detract from its usefulness. But, this two-foldedness demonstrates that its essence consists in its conveyance of Motion, i. e. from observed phenomenon to constructed instrument, rather than in its formulation of abstract static relations.