“Nothing which consists of corporeal matter is absolutely light, but that is comparatively lighter which is rarer, either by its own nature, or by accidental heat. And it is not to be thought that light bodies are escaping to the surface of the universe while they are carried upwards, or that they are not attracted by the earth. They are attracted, but in a less degree, and so are driven outwards by the heavy bodies; which being done, they stop, and are kept by the earth in their own place.”

— Johannes Kepler , book Mysterium Cosmographicum

As translated and quoted by Bryant, ibid.
Mysterium Cosmographicum (1596), Astronomia nova (1609)

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Johannes Kepler 51

German mathematician, astronomer and astrologer 1571–1630

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“Nothing which consists of corporeal matter is absolutely light, but that is comparatively lighter which is rarer”

Johannes Kepler book Astronomia nova

As quoted by Bryant, ibid.
Astronomia nova (1609)
Context: Nothing which consists of corporeal matter is absolutely light, but that is comparatively lighter which is rarer, either by its own nature, or by accidental heat. And it is not to be thought that light bodies are escaping to the surface of the universe while they are carried upwards, or that they are not attracted by the earth. They are attracted, but in a less degree, and so are driven outwards by the heavy bodies; which being done, they stop, and are kept by the earth in their own place.

“But although the attractive virtue of the earth extends upwards, as has been said, so very far, yet if any stone should be at a distance great enough to become sensible compared with the earth’s diameter, it is true that on the motion of the earth such a stone would not follow altogether; its own force of resistance would be combined with the attractive force of the earth, and thus it would extricate itself in some degree from the motion of the earth.”

Johannes Kepler book Astronomia nova

As quoted by Bryant, ibid.
Astronomia nova (1609)

“If the attractive virtue of the moon extends as far as the earth, it follows with greater reason that the attractive virtue of the earth extends as far as the moon and much farther; and, in short, nothing which consists of earthly substance anyhow constituted although thrown up to any height, can ever escape the powerful operation of this attractive virtue.”

Johannes Kepler book Astronomia nova

As quoted by Bryant, ibid.
Astronomia nova (1609)

“…wheresoever the earth may be placed, or whithersoever it may be carried by its animal faculty, heavy bodies will always be carried towards it.”

Johannes Kepler book Astronomia nova

As quoted by Bryant, ibid., p. 36
Astronomia nova (1609)

“I have also cleared the electromagnetic theory of light from all unwarrantable assumption, so that we may safely determine the velocity of light by measuring the attraction between bodies kept at a given difference of potential, the value of which is known in electromagnetic measure.”

James Clerk Maxwell (1831–1879) Scottish physicist

Letter to C. Hockin, Esq. (Sept 7, 1864) as quoted by Lewis Campbell, William Garnett, The Life of James Clerk Maxwell: With Selections from His Correspondence and Occasional Writings https://books.google.com/books?id=B7gEAAAAYAAJ (1884)

“I hold that the first form of a body is the first corporeal mover. But this is light, which as it multiplies itself and expands without the body of matter moving with it, makes its passage instantaneously through the transparent medium and is not motion but a state of change. But, indeed, when light is expanding itself in different directions it is incorporated with matter, if the body of matter extends with it, and it makes a rarefaction or augmentation of matter; for when light is itself charged with the body of matter, it produces condensation or rarefaction. So when light generates itself in one direction drawing matter with it, it produces local motion; and when light within matter is sent out and what is outside is sent in, it produces qualitative change. From this it is clear that corporeal motion is a multiplicative power of light, and this is a corporeal and natural appetite.”

Robert Grosseteste (1175–1253) English bishop and philosopher

see De Luce Tr. Ludwig Baur (1912) pp. 51-52
De Luce seu de Inchoatione Formarum (c. 1215-1220)

“Fir: it contains a great deal of air and fire with very little moisture and the earthy, so that, as its natural properties are of the lighter class, it is not heavy. Hence, its consistence being naturally stiff, it does not easily bend under the load, and keeps its straightness when used in the framework. But it contains so much heat that it generates and encourages decay, which spoils it; and it also kindles fire quickly because of the air in its body, which is so open that it takes in fire and so gives out a great flame.”

Vitruvius book De architectura

Source: De architectura (The Ten Books On Architecture) (~ 15BC), Book II, Chapter IX, Sec. 6

“Whence do you have it that the terrestrial globe is so heavy? For my part, either I do not know what heaviness is, or the terrestrial globe is neither heavy nor light, as likewise all other globes of the universe. Heaviness to me (and I believe to Nature) is that innate tendency by which a body resists being moved from its natural place and by which, when forcibly removed therefrom, it spontaneously returns there. Thus a bucketful of water raised on high and set free, returns to the sea; but who will say that the same water remains heavy in the sea, when being set free there, does not move?”

Galileo Galilei (1564–1642) Italian mathematician, physicist, philosopher and astronomer

Letter to Francesco Ingoli (1624)

“The changing of bodies into light, and light into bodies, is very conformable to the course of Nature, which seems delighted with transmutations.”

Isaac Newton book Opticks, or a Treatise of the Reflections, Refractions, Inflections and Colours of Light

Query 30 : Are not gross bodies and light convertible into one another, and may not bodies receive much of their activity from the particles of light which enter into their composition?
Opticks (1704)

“Do not Bodies and Light act mutually upon one another; that is to say, Bodies upon Light in emitting, reflecting, refracting and inflecting it, and Light upon Bodies for heating them, and putting their parts into a vibrating motion wherein heat consists?”

Isaac Newton book Opticks, or a Treatise of the Reflections, Refractions, Inflections and Colours of Light

Query 5
Opticks (1704)

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Johannes Kepler 51

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