through the scantiness of data. This was the case at the period now
referred to, and at such a period, by the authority of Newton, all
antagonists were naturally overborne.

The march of mind is rhythmic, not uniform, and this great Emission
Theory, which held its ground so long, resembled one of those circles
which, according to your countryman Emerson, the intermittent force of
genius periodically draws round the operations of the intellect, but
which are eventually broken through by pressure from behind. In the
year 1773 was born, at Milverton, in Somersetshire, a circle-breaker
of this kind. He was educated for the profession of a physician, but
was too strong to be tied down to professional routine. He devoted
himself to the study of natural philosophy, and became in all its
departments a master. He was also a master of letters. Languages,
ancient and modern, were housed within his brain, and, to use the
words of his epitaph, 'he first penetrated the obscurity which had
veiled for ages the hieroglyphics of Egypt.' It fell to the lot of
this man to discover facts in optics which Newton's theory was
incompetent to explain, and his mind roamed in search of a sufficient
theory. He had made himself acquainted with all the phenomena of
wave-motion; with all the phenomena of sound; working successfully in
this domain as an original discoverer. Thus informed and disciplined,
he was prepared to detect any resemblance which might reveal itself
between the phenomena of light and those of wave-motion. Such
resemblances he did detect; and, spurred on by the discovery, he
pursued his speculations and experiments, until he finally succeeded
in placing on an immovable basis the Undulatory Theory of Light.

The founder of this great theory was Thomas Young, a name, perhaps,
unfamiliar to many of you, but which ought to be familiar to you all.