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THE EVOLUTION OF WORLDS

in the results are worthy of notice. For it is by thus being particular and systematic that the accuracy of the determinations made there, in other lines besides this, has been secured.

In size, Venus of all the planets most nearly approaches the Earth. She is 7630 miles in diameter to the Earth's 7918. Her density, too, is but just inferior to ours. And she stands next us in place, closest in condition and constitution in the primal nebula. Yet in her present state she could hardly be more diverse. This shows us how dangerous it is to dogmatize upon what can or cannot be, and how enlightening beyond expectation often is prolonged and systematic study of the facts.

The next planet outward is our own abode. It is one of which most of us think we know considerable from experience and yet about which we often reason cosmically so ill. If we knew more, we should not deem ourselves nearly so unique. For we really differ from other members of our system not more than they do from one another. Much that appears to us fundamental is not so in fact. Thus many things which seem matters of course are merely accidents of size and position. Our very day and night upon which turn the habits of all animals and, even in a measure, those of plants, are, as we have seen, not the possession of our nearest of cosmic kin. Our seasons which both vegetally and vitally mean so