246 TIME, SPACE, AND INVISIBLE WORLDS. 



and, to all appearance, inhabitable planets. Ignoring for the 

 present Mars, Venus, and Mercury, and taking Earth only as our 

 guide in analogy, let us regard every fourth globe only as inhabited 

 by organised life, short of Man. We are thus left with three 

 thousand Planets controlled by Suns within the limits of naked 

 eye vision, in which, according to all available evidence, furnished 

 by Analogy, Probability, and Continuity, life, vegetable and animal, 

 exists more or less abundantly. 



The question now arises (and the answer will surprise those 

 who have not considered the matter), " In how many of these 

 three thousand worlds may we reasonably suppose the evolution 

 of life to have culminated in responsible and intelligent beings 

 like ourselves ? " This question is answerable only by asking 

 another, "When did the life-bearing stage commence upon Earth?" 

 Even Geology, with all its wonderful discoveries, fails us here. 

 Authorities vary in their estimates, but all speak of millions of 

 years. Shall we say, just to give point to thought, not less than 

 seven, more nearly twenty, and just possibly forty millions, these 

 being followed by the small fraction of seven thousand years cover- 

 ing human probational history ; that is, the history of Man as the 

 final product of physical evolution, he alone combining within 

 himself all the tremendous issues of the past of Earth, with all the 

 possibilities of an illimitable and evolving future. These figures, 

 which, if the reasoning be just, or approximately so, by no means 

 exaggerate the final result, indicate, by the following simple ratios, 

 the number of planets now inhabited by human or intelligent life, 

 and now controlled by those Star-suns which the naked eye can 

 descry on any clear night in the Heavens above and around us. 

 The total life-bearing period of each planet (continuing for seven, 

 twenty, or forty millions of years) is to the total human life period 

 (say seven thousand years), as the number of present life-bearing 

 planets (three thousand, as before named) is to the number of 

 planets now inhabited by intelligent beings like ourselves. The 

 ratio or answers are as follows : — 3 planets, if the average life 

 period of the 3,000 be 7 million years ; 1-05 if 20 millions ; and 

 o'525 if 40 millions. 



Thus, by calculation based upon averages, supported by 

 analogy, probability, and continuity, we reach the singular result 



