Treatise on light : In which are explained the causes of that which occurs in reflexion, & in refraction and particularly in the strange refraction of Iceland crystal

A seventeenth‑century scholar presents his reflections on the mysteries of light to the Royal Academy of Science, offering a vivid picture of the era’s lively debates on optics. Drawing on personal observations made while in France, he tackles the fundamentals of reflection and refraction and turns a special focus toward the puzzling behavior of Iceland crystal and rock crystal, inviting listeners into the early experimental spirit that shaped modern physics.

The work blends geometric reasoning with empirical testing, arguing that a high degree of probability—often indistinguishable from certainty—can be achieved when theory matches repeated observation. Its modest aim is to illuminate the causes behind vision and the functioning of telescopes, while openly acknowledging unanswered questions about colors and luminous bodies. Listeners will appreciate both the historical context and the author’s invitation for future scholars to continue exploring the nature of light.