Transparent bodies and glass · Lexicon

From the book

The Summary of Physics Restored

Attributed to Jean d’Espagnet · Diotimos Editions · 2026

Orientation

At a Glance

The wordDiaphanum names a transparent body. Glass becomes the book's chief test of how a spiritual power can pass where the bodily vehicle of a ray cannot.
In the bookThe author denies that the original solar rays literally pass through glass. He explains the far-side light through transmitted spirit and through the glass itself becoming luminous.
In this edition“Illuminated” and “luminous” translate distinct predicates in 205. The account of glass from ashes in 217 is a separate material argument linked by transparency, not a second optical experiment.
A place to readRead 202–205 in sequence before 217. The claim about glass depends upon the prior composition of rays and the distinction between air and spirit.

Meaning

A transparent medium receives and communicates light. In this theory, being open to a spirit is not equivalent to allowing the same parcel of luminous air or the same composite ray to pass straight through. The Latin vitrum is glass; corpus diaphanum is the wider class that glass illustrates. The author gives transparency an active mediating role. It is a capacity to receive a luminous principle and communicate its effects, not merely an absence of obstruction measured without a theory of what is transmitted.

Use in the book

The earlier description of air in canon 77 calls it foremost among transparent things. It is a receptive, communicating medium, readily affected yet not tenaciously retaining what it receives. This furnishes a background for the much later distinction between rays and a spiritual radiance. In canon 202 visible rays use air as their vehicle and are stopped by dense bodies. Canon 203 nevertheless allows an illumination through spiritual radiance without the direct presence of source and rays. Glass in 204 is the hard case that tests these assignments.

A glass body struck by solar rays gathers them and receives the Sun's image. It then becomes luminous, a miniature Sun, emitting its own rays towards the far side. The author acknowledges the appearance that solar rays are refracted and traverse the glass; he explicitly denies that this is what really happens. The original rays are stopped because of the air adhering to them. Only the spirit of light is transmitted. Far-side rays are therefore described as the rays of a glassy Sun. An account that says merely “the author discusses refraction through glass” would miss his rejection of the apparent mechanism.

Canon 205 unfolds the explanation into two means. First, glass is pervious to the spirit of radiance: it receives and transmits that spirit, which enters the air beyond. Second, the transparent body is itself kindled into luminosity by the received light, like a wick. It becomes not merely illuminated but luminous, acquiring the power to pour out radiance. The two statements are presented together, rather than as rival hypotheses from which the reader is asked to choose. Dense and opaque bodies, by contrast, are allowed to communicate radiance by reflection, not in the same way as the transparent luminous medium.

Glass reappears in a different evidential role in canon 217. The author reasons from glassmakers' work with ashes: a continuous solid body is produced through flowing, and he takes flowing to require moisture. Radical moisture, supposedly surviving fire in ashes, is accordingly said to terminate in the noble transparent body of glass. The argument connects the visible result with an invisible enduring principle. It does not say that ordinary water remains trapped as such in the finished glass, nor does the observed production independently demonstrate all the theological claims later made for the material root.

The two discussions deserve connection without collapse. In optics, glass shows how spirit and bodily carriers differ; in the account of matter, glass makes a hidden persistent capacity manifest. In both, transparency is evidence for a closeness to ethereal nature. Yet the natural-philosophical explanation, the artisan's practice, and the interpretation of what that practice proves remain different levels of the argument. This entry describes those levels without offering an operational glassmaking process or treating the author's inferences as present materials science.

Places to read

Canon 77; 1653, p. 55LatinAir as the first transparent and communicating medium.
Canon 202; 1653, pp. 146, 147LatinAir-carried rays stopped by dense bodies.
Canon 203; 1653, p. 147LatinRadiance without direct rays prepares the transmission problem.
Canon 204; 1653, pp. 147, 148LatinThe explicit denial of literal passage by the same rays through glass.
Canon 205; 1653, pp. 148, 149LatinTwo means of transparent mediation; luminous versus illuminated.
Canon 217; 1653, p. 157LatinGlass from ashes as evidence for persistent radical moisture.

Flowing, from which the author infers a surviving moisture. — Canon 217; 1653, p. 157.

Read: Canon 217 · Latin.

Continuous quantity — quantitas continua

Continuous quantity, a requirement of the resulting solid glass in the argument. — Canon 217; 1653, p. 157.

Read: Canon 217 · Latin.