From the paragraph Optics in the wiki article
Newton argued that light is composed of particles or corpuscles, which were refracted by accelerating into a denser medium. He verged on soundlike waves to explain the repeated pattern of reflection and transmission by thin films (Opticks Bk.II, Props. 12), but still retained his theory of ‘fits’ that disposed corpuscles to be reflected or transmitted (Props.13).
If you look at the history of optics it is dominated by ray optics, straight lines. Particles travel in straight lines . I think that was the correlation he must have made.
In his Hypothesis of Light of 1675, Newton posited the existence of the ether to transmit forces between particles. In 1704, Newton published Opticks, in which he expounded his corpuscular theory of light. He considered light to be made up of extremely subtle corpuscles, that ordinary matter was made of grosser corpuscles and speculated that through a kind of alchemical transmutation "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 their Composition?"
He was not far off actually, once photons were discovered. Just missed duality.
It seems Lucretius had had the same idea ceturies before
In 55 BC, Lucretius, a Roman who carried on the ideas of earlier Greek atomists, wrote:
The light and heat of the sun; these are composed of minute atoms which, when they are shoved off, lose no time in shooting right across the interspace of air in the direction imparted by the shove.
—Lucretius, On the nature of the Universe