of the ultimate particles of matter out of which worlds are formed, reveal the speculative tendency as well as the intellectual status of the human mind in different epochs of the history of civilization. The present era might be designated as an interrogatory age, for the evident tendency is to question eagerly, to accept nothing on the evidence of tradition, and but little, comparatively, on the merits of faith.
Plausible explanations of various phenomena have so often been accepted with confidence, only to be overthrown and supplanted by others equally unstable, that the mind has become suspicious, and demands the most rigid physical tests to corroborate new theories. The experimental feature of scientific study has thus attained an importance and perfection never before approached, and this cause largely contributes to popularize even the most abstruse subject of inquiry. The object of this brief paper is to present, albeit in a feeble manner, the claims of one of these little paths of knowledge to the exploration of the general reader, who, like the summer tourist, sometimes prefers to leave the beaten track, to enjoy the novelty of a rougher road.
The learned judge who, being requested to define the distinction between mind and matter, replied, "One is no matter, the other—never mind," solved the difficulty in a terse if not very satisfactory or exhaustive way. The question, "What is matter?" is one that has exercised the intellects of the profoundest thinkers in all ages, and the conundrum is, apparently, as far from being definitely answered in this nineteenth century as in the classic days of the Greek philosophers. It would seem, indeed, that the modern views of matter, based upon strictly scientific data and mathematical reasoning, have approached very closely to those propounded by the Attic philosophers, which were evolved purely from the inner consciousness of the poetic sages, the ancient theories being rather expressions of sentiment or feeling than of observed realities or facts. We may find a parallelism to this in the grand musical compositions of the old masters: knowing nothing of the modern science of music or the laws of acoustics, they felt and recorded harmonious combinations which are now shown by analysis to conform to most rigid mathematical laws. The poetical fancies of Lucretius on "The Nature of Things," which have been preserved to us through a lapse of two thousand years, will receive new interest in the light of modern scientific revelation.
The delicacy of the apparatus devised by physicists and the refinement of experimental demonstration rendered possible thereby are among the greatest marvels of this wonderful age. The physicist is pushing his researches into paths which but a few years since were thought to be for ever hidden somewhere in the vast realm of the "unknowable," and the boundary line between so-called physical and metaphysical science is continually narrowing. Just as the skilled mountaineer or the aëronaut ascends gradually into the rarefied upper atmosphere, in order that the system may accommodate itself to its