He first explained light as a stream of high-speed particles, thus making its straight-line propagation reasonable.
Then he put forward another hypothesis:
The particles composing light, when passing through a boundary, enter a special temporary state.
During propagation, they restore themselves at equal intervals, and when they restore, they pass through the next interface more easily, whereas between restorations, they're more likely to be reflected.....
Pretty mystical, isn't it?
The particles periodically return to their original state, pass through when restored, reflect when not restored…
This does explain the phenomenon of Newton's rings, but this explanation makes the particle theory sound awfully similar to the wave theory.
According to the wave theory:
This "equal interval" is the wavelength; when phases coincide, it passes through easily, when the phases are opposite, reflection is more likely…
