Several modern observers have found that the older astronomers were all in error in giving Venus a rotation-period almost exactly the same as ours, an error due to the indefinite and variable markings of its surface. They have now deduced a period about equal to that of its revolution round the sun--a rate which has been confirmed by spectrum-analysis, and further confirmed by the fact that this planet has no measurable polar compression. As during transits of Venus over the sun’s disc the conditions for the accurate measurement of the compression, if any exist, are the best possible, and as none has been found, this alone affords a demonstration that the rate of rotation must be very slow, because the laws of motion _necessitate_ a definite amount of equatorial protuberance corresponding to that rate. Half the surface has, therefore, perpetual day and the other half perpetual night, leading to violent contrasts of heat and cold for the two hemispheres with, in all probability, correspondingly violent winds, rains, and electrical disturbances--conditions so entirely opposed to the uniformity of temperatures and stability of meteorological phenomena during long geological epochs which are essential for the full development of organic life, that such development is perhaps less probable on this planet than on any other. I think I have now shown not only that no other planet in the solar system makes any approach to the possession of the varied and complex adaptations which are essential for a full development of organic life, but also that on the Earth itself the conditions are so numerous and so nicely balanced that very moderate deviations in excess or defect of what actually exists in the case of any one of them--and of others not referred to here--might have rendered it equally unsuitable, so that either no organic life at all, or only a very low type of life, could have been developed or supported. [Sidenote: There is Purpose in our World] If, then, the more superficial indications of design in the relations of animals to their environment, and of man to the universe, have been shown by modern science to have required no _special_ interference of a higher power to bring them about, but that they have been due to natural laws acting in accordance with and in subordination to the deeper laws and forces that determine the very constitution of matter and the unknown power and principle we term “life,”--yet, on the other hand, we find that a more careful study of the outer universe, or cosmos, reveals a new set of adaptations not less wonderful or more easily explicable by chance coincidence than those presented by the organic world.