THEIMPRESSOFLIGHT^97
of theatmosphere,and plant foods of thesoil, and
buildsupthehydrocarbonsandotherfuelsofanimal
andvegetabletissue,wefinditalwaysmainlyinthe
solarrays. Isaymainly,because,ofcourse,thelight
andheatofthestars,theimpactofmeteors, andthe
probable slow contraction of the earth, are all real
sources of energy,and contribute theirquota. But,
as compared withtheenergy derived fromthe sun,
theirtotalamountisprobablysomethingliketheratio
ofstarlighttosunlight;sosmallthatitisquiteclear,
aswesaidbefore,thatamonth'sdeprivation ofthe
solarrays wouldinvolvetheutterdestruction of all
activityupontheearth."
—
"TheSun/' Young,
Allthisistrueenough. Butwhilewekeepinmind
theinfluence ofthe sun,letus notforgetthe other
side of the subject. The sun, itis true, acts with
marvelous power upon the earth; but suppose the
earth,likethemoon,perhaps,didnotrespondtothat
influence—whatthen? While we get atrue value
ofthepositionandpowerofthesun,letusnotforget
thattotheearthhasbeenimpartedthepowertore-
spondto the sun'sinfluence. If this power of re-
spondinghadnotbeenimpartedtotheearth,thesun
might shinehere forever,withouteffect. Butwhile
the sun, like the seal, can give its impression, the
earth,liketheclay,hasthepowertorespond.
If I shouldpress a sealupon thehardsurfaceof
agraniterock,therewouldbenoimpress. Thegranite
cannotrespondtotheseal. ButwhenIplacetheseal
uponthesoftened,yielding,responsive clay,orwax,
Igetanexactimpressionoftheseal.