MAN FROM THE FARTHEST PAST 
that the flow of solar energy is to be estimated in horse- 
power in terms of the number of square yards on the sur- 
face of a sphere ninety-three million miles in radius. 
What supplies this copious flood of energy? Probably 
the annihilation of atoms. This, indeed, so eminent an 
astronomer as Professor Jeans of England states to be not 
only a reasonable but a necessary article of scientific belief. 
Writing on “Astronomy” in the thirteenth edition of the 
Encyclopaedia Britannica, Professor Eddington declares 
the energy equivalent of the destruction of the entire sub- 
stance of our sun to be sufficient to sustain its output of 
radiation through fifteen trillions of years. This is the 
order of time which the universe is now supposed to 
represent. 
Thus, in brief summary, man’s home is in a universe con- 
taining some hundreds of thousands of galaxies each com- 
posed of millions or billions of stars. Among these there 
may be many systems of planets such as that which our 
star, the sun, holds in his train, and among them may be 
many inhabited worlds. The starry hosts are scattered 
through a space measured in millions of times the six 
trillions of miles that light traverses in a year. They seem 
likely to have been existing through time enduring trillions 
of years, and likely to continue quite as long in time to 
come. From the prodigious stores of energy, partly gravi- 
tational, partly radiant, which our star, the sun, supplies, 
man collects the fragment that he needs to carry on his 
comparatively small concerns. In short, a man, one of 
nearly two billion living human individuals enduring 
but for threescore years, does not loom large compared 
to the universe 1n which he dwells, to its duration or its 
energies. 
Man’s existence on his little earth depends on extraor- 
dinary circumstances. As to how life began here, science 
offers no guess, but how slight are the changes which 
might destroy life has recently become plain. Water in 
liquid form is indispensable. It is the only natural liquid 
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