"even if we take in the smaller stars that stand in the feet and head, no ingenuity can make it in this or any other way resemble a bear," adding the absurd explanation given by Aristotle, "that the name is derived from the fact that of all human animals the bear was thought to be the only one that dared to venture into the frozen regions of the north, and tempt their solitude and cold." As though the shepherds and tillers of the soil, who first gave names to the stars, were likely to consider such far-fetched reasons, even if they had known either the habits of the polar bears or had considered the relation of the northern star-groups to the polar regions of the earth. Now the question whether any real resemblance attracted the attention of the earlier observers in such cases as this is by no means without interest. If such a resemblance formerly existed, and does not now exist, it would follow that quite a considerable proportion of the stars have changed in brightness. Considering that each star is a sun, the centre, most probably, of a system like that which circles around our own sun, such a conclusion would be very startling indeed. It would have a special interest for ourselves, somewhat in the same way that the news that many railway accidents occur has an interest for those who travel much by rail. If accidents frequently happen to those other suns, in such sort that they either lose or gain greatly in brightness, an accident of one or other kind might well happen to our own sun, in which case the inhabitants of this earth would perish. For many of the stars, by our supposition, would have changed so much as either to lose their character as the defining stars of a constellation or by accession of brightness to acquire that character which in old times they had not possessed. Now, assuredly, a change of brightness competent to affect _our_ sun's character (as viewed from any remote star system) in equal degree, would be destructive to the inhabitants of the earth. None at least of the higher races of animals or plants could bear the intense cold resulting from a change of the former kind, or the intense heat resulting from a change of the latter kind. Yet, if the constellations were once named because of their imagined resemblance to various objects, and if no such resemblance can now be even imagined, a change of one or other kind in the condition of our sun must be regarded as probable,--much in the same way that a regular traveller by train on any line must be regarded as exposed to danger, if accidents are known to be continually happening on that line.