Oh Yes: In the 17th century Sir Issac Newton declared that light was corpuscular, that is, made of particles. Though there were some outstanding questions, this view was accepted for over 100 years. Then in 1803 Thomas Young proved that light produced an interference pattern after it passed through a narrow slit. Such an interference pattern is a distinctive indicator of a wave. His experiment, along with subsequent work by Fresnel, soon persuaded scientists that light must be a wave. In the 1860's James Clerk Maxwell produced some brilliant mathematics, today known as Maxwell's equations, and proved that electricity and magnetism were integrally related as one phenomenon. As a byproduct, his equations showed that there should exist a certain kind of wave, consisting of a special interlocked pattern of oscillating electric and magnetic waves, an electromagnetic wave. Based on other empirically known constants associated with electricity and magnetism, his equations yielded a calculated value for the speed of this electromagnetic wave. The speed was exactly the same as the velocity of light that had been calculated by other experiments. This remarkable discovery demonstrated that not only were electrify and magnetism one phenomena, but light, a phenomena seemingly quite unrelated, was also an aspect of the same electromagnetic phenomena. After these developments, and for a some time thereafter, scientists understandably had thorough confidence that light was indeed a wave.
Against the background of this solid conclusion of science, Blavatsky, writing in 1888 in the Secret Doctrine (volume I of the Secret Doctrine, called "Science and the Secret Doctrine Contrasted), gave her readers an intimation of the future when she hinted with a question.
True, the corpuscular theory of old is rejected, and the undulatory theory has taken its place. But the question is, whether the latter is so firmly established as not to be liable to be dethroned as was its predecessor? THIS HAS BEGAN!!