Galileo first states his own views, and then pretends that he will oppose them. He goes on to say that he believes in the earth's immobility, and takes "the contrary only for a mathematical _Capriccio_," as he calls it; something to be considered, because possessing an academical interest, but on no account having a real existence. Of course any one (even a censor) ought to be able to see that it is the Capriccio, and not its opposite, that Galileo really advocates. Three persons appear in the "Dialogue": Salviati, who believes in the Copernican system; Simplicio, of suggestive name, who thinks the earth cannot move; and, finally, Sagredus, a neutral gentleman of humorous propensities, who usually begins by opposing Salviati, but ends by being convinced. He then helps to punish poor Simplicio, who is one of those persons apparently incapable of comprehending a reasonable argument. Here is an interesting specimen of the "Dialogue" taken from Salusbury's translation: Salviati refers to the argument, then well known, that the earth cannot rotate on its axis, "because of the impossibility of its moving long without wearinesse." Sagredus replies: "There are some kinds of animals which refresh themselves after wearinesse by rowling on the earth; and that therefore there is no need to fear that the Terrestrial Globe should tire, nay, it may be reasonably affirmed that it enjoyeth a perpetual and most tranquil repose, keeping itself in an eternal rowling." Salviati's comment on this sally is, "You are too tart and satyrical, Sagredus." There is no doubt that the "Dialogue" finished the Ptolemaic theory, and made that of Copernicus the only possible one. At all events, it brought about the well-known attack upon Galileo from the authorities of the Holy Office. We shall not recount the often-told tale of his recantation. He was convicted (very rightly) of being a Copernican, and was forced to abjure that doctrine. Galileo's life may be summed up as one of those through which the world has been made richer. A clean-cutting analytic wit, never becoming dull: heated again and again in the fierce blaze of controversy, it was allowed to cool only that it might acquire a finer temper, to pierce with fatal certainty the smallest imperfections in the armor of his adversaries. THE PLANET OF 1898