Following the track sparsely blazed by Young, Whewell, Ware and Airy, Donders cleared the ground and laid the foundations of modern ophthalmology. The obstructions in his path were many and formidable, but his genius enabled him to surmount them, and his epoch-making book on "Accommodation and Refraction of the Eye" at once raised ophthalmology from a purely empiric practice to a quasiexact science. When one considers that up to his time the true nature of hypermetropia, myopia and astigmatism was unknown, that asthenopia was classed as a disease, and that the instruments at his disposal were few and crude, one marvels at the mind that was able, out of this slough of ignorance, to evolve a science that immediately placed ophthalmology at the forefront of the medical specialties. How accurate and exhaustive were his investigations, and how sound were his conclusions is evidenced by the fact that although, since his