through such a Medium are rejected with it. And for rejecting such a Medium
we have \also/ the authority of those the oldest & most celebrated Philosophers of
Greece & Phenicia, \ (Mochas, Phirecides, Thales, Pythagoras / who made a Vacuum, Atoms & the gravity of Atoms the
first principles of their philosophy

I have therefore proposed the Question whether the rays of light
may not be small bodies emitted by shining substances. Certainly the
resemblance between them \rays & bodies such bodies/ is very great. For such \such/ bodies will pass
through uniform Mediums in right lines without bending into the shadow
w^ch is the property of the rays of light. Pellucid substances act upon
the rays of light at a distance in refracting reflecting & inflecting
them, & the rays mutually agitate the parts of those substances
at a distance for heating them, & this action & reaction very much
resembles an attractive force. If refraction be performed by attraction
of the rays, the sines of incidence must be to the sines of refraction in
a given proportion as we shewed in o^r Principles of Philosophy; & this
Rule is true by experience. If the rays of light in going out of
a glass into a Vacuum fall too obliquely on the Vacuum, they are
totaly reflected w^ch seems to argue an attraction of the glass.
Colours & Refractions depend not on new modifications of light but
on the original & unchangeable properties of its rays, & such proper
ties are best conserved in bodies projected. Pressions & motions are
apt to receive new modifications in passing through several Mediums
but the properties of bodies projected will scarce be altered thereby. No-
thing more is requisite for producing all the variety of colours & degrees
of refrangibility then that the rays be bodies of different sizes the least
of w^ch \may/ make violet the \weakest &/ darkest of colours & be more easily diverted by
refracting surfaces from the right course, & the rest, as they are bigger
& bigger may make the \stronger &/ more lucid colours, blue green yellow & red
& be more & more difficultly diverted. And lastly the unusual refraction
of Island Crystal looks very much as if it were performed by some
kind of polar \attractive/ vertue \ attraction / \lodged in certain sides/ both [illeg] |of| the rays & i |o|f the particles of the crys-
tall. For were it not for some kind of polar \disposition or/ vertue in \some sides of/ the particles
of the crystal w^ch [derives] \is not in their other sides & w^ch inclines & bends/ the rays towards the coasts of unusual re-
fraction the rays \ w^ch fall perpendicularly on the crystal/ would not be refracted towards that coast when they
fall perpendicularly on the glass \ crystal / |rather then towards any other coast, Both at their incidence & at their emergence, so as to emerge perpendicularly by a contrary situation of y^e coast of unusual refraction at the second surface; the crystal acting upon the rays after they have past through it & are emerging into y^e air or if you please into a vacuum.| And since the crystal by this |disposition or|
vertue does not act upon the rays unless when \one of/ their sides of unusual
refraction are look | are \turned/ towards that coast this argues a vertue \or disposition/ in those sides
of the rays which answers to & sympathizes with that vertue \or disposition/ of the
crystal, as the poles of two Magnets answer one to another. And as
magnetism is not found in all bodies may be intended & remitted & is
found only in the Magnet & in iron, so this vertue of refracting the
perpendicular rays is greater in Island Crystal less in Crystal of the
rock & is not yet found in other bodies. But what ever this vertue be