light from light The mediaeval scholar Robert Grosseteste saw that the hypothetical space, in which Euclid in 300 BC imagined his numbers, was the same everywhere and in every direction. Subsequently, Grosseteste postulated that this was also true with regard to the propagation of the light. About the light, he wrote De Luce: On light or the beginning of things. Below follow a few quotes from this treatise.
I
am of the opinion that the first physical manifestation (that some call ‘a body’) is the light. For by its nature, the light spreads in all directions in such a way that a point of light immediately becomes a sphere of light of any size, unless some opaque object stands in the way. The expansion of such a body (light) is a necessary, incidental circumstance, despite the fact that both this body as well as matter are as such basic substances without dimensions. A body that in itself is a basic substance cannot attribute measurements or dimensions in space that is itself immeasurable and dimensionless, unless it multiplies itself and immediately spreads itself, thus expanding the body. For the form or the body (that is the light) cannot leave space, because it is inextricably linked with it and matter cannot be separated from the form. However, I have postulated that it is the light that, by its very nature, possesses the quality to multiply itself and to spread in all directions. Whatever it may be that performs this activity, light or another agent, it acts by virtue of its sharing in the light, to which this activity essentially belongs. The body (the manifested form) is, therefore, either the light itself or the agent that performs the aforementioned activity and attributes dimensions in space (because it shares in the light and acts with its power). But the first form cannot create dimensions in space by the effect of what is manifested after it. This is why the
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