49 
But this is not all: we are invited to bear in mind 
the fact of the enormous increase in a geometrical ratio, 
which is both actual and potential, in order that we 
may understand “the ever-recurring destruction of the 
enormous annual increase” which accompanies a fixed 
population. 
Mr. Fiske adopts the same method of treating the 
subject in the following passage :— 
“ Let us take the case of a plant which yields one hundred seeds 
yearly, and suppose each of these seeds to reach maturity so as 
to yield its hundred offspring in the following year : in the tenth 
year the product would be one hundred thousand trillions. . . . 
We may now begin dimly to realise how prodigious is the slaughter 
which unceasingly goes on throughout the organic world. For ob 
viously when a plant, like the one just cited, maintains year by year 
a tolerable uniformity in its numbers, it does so only because on 
the average ninety-nine seeds perish prematurely for one that sur 
vives long enough to produce other seeds.”—(Outlines of Cosmic 
Philosophy, vol. ii.,p. n.) 
Here we have an output of life amounting to one hun 
dred thousand trillions suggested ; and at the same time 
it is admitted that the actual output only amounts to 
one thousand—that is, one hundred per annum for ten 
years. 
The principle of a tendency to increase in a geometrical 
ratio cannot have the power which resides in heat when 
it is latent. In that case, whether latent or not, heat 
represents so much force in a particular condition. But 
a tendency which remains a tendency occupies a different 
category. We must not venture to build on the calcula 
tions of a potential increase which cannot possibly become 
actual, any more than we ought to treat as actual history 
the story of a world that might have been. There is 
about as much common sense in such rhetorical science 
as there is in such imaginative history. And nobody 
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