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Galaxy

Aiton's Encyclopedia (1910)

. See Milky Way Galen (130-201), a celebrated physician of Grecian birth and Roman practice. Having exhausted the educational resources of Greece, he gained a wide reputation as a healer of disease. He went to Rome, as many educated Greeks of that period did. He attended the Emperor Marcus Aurelius in his northern wars with the barbarians, and expressed gratification on account of the opportunity for dissection offered by barbarian warriors slain in battle. Galen wrote a large number of works of which eighty-three are extant, covering the field of medicine surprisingly well. Galen's treatises were translated from the original Greek into Arabic and Latin and English, and later into other modern languages. They are the channel through which Greek medicine has been made known. Galen's authority remained supreme until about the time when our Atlantic coast was occupied by colonies. As late as the middle of the sixteenth century a London physician, who had assailed the teachings of Galen, was obliged to take back what he had said and to hand in a written apology on penalty of expulsion from the College of Physicians. Later Galen's teachings were stoutly opposed on account of excessive blood letting or cupping, and the use of herbs too exclusively as remedies. Oliver Wendell Holmes, lecturing before the medical students of Harvard, spoke of "remedies which are both Galenic and chemical," that is, both vegetable and mineral, and again, "These Galenists were what we should call herb-doctors today." The housewife, with an oldfashioned store of boneset, sage, sassafras, pennyroyal, and spikenard, is a Galenist without knowing it. See Medicine ; Averroes

What Has Changed in the Last Century

Aiton's 1910 entry needs only three words — "See Milky Way" — because at that date "the Galaxy" meant our own star system, and most astronomers took the faint spiral nebulae to be objects inside it. That view collapsed within a decade and a half: the Shapley–Curtis debate of 1920 aired the question publicly, and in 1923–24 Edwin Hubble found Cepheid variable stars in the Andromeda nebula that placed it far beyond the Milky Way, making it a galaxy in its own right. Hubble went on in 1929 to link galaxies' redshifts to their distances, the observation behind the expanding universe. Today the word is a plural noun: surveys and the Hubble and James Webb space telescopes have mapped galaxies by the million and put the likely total in the hundreds of billions.

Written for this edition, 2026.