We must never for an instant lose sight of the fact of the enormously rapid increase of all organisms, which has been illustrated by actual cases, given in our second chapter, no less than by calculations of the results of unchecked increase for a few years.

Then, never forgetting that the animal and plant population of any country is, on the whole, stationary, we must be always trying to realise the ever-recurring destruction of the enormous annual increase, and asking ourselves what determines, in each individual case, the death of the many, the survival of the few.

We must think over all the causes of destruction to each organism,--to the seed, the young shoot, the growing plant, the full-grown tree, or shrub, or herb, and again the fruit and seed; and among animals, to the egg or new-born young, to the youthful, and to the adults.

Then, we must always bear in mind that what goes on in the case of the individual or family group we may observe or think of, goes on also among the millions and scores of millions of individuals which are comprised in almost every species; and must get rid of the idea that _chance_ determines which shall live and which die.

For, although in many individual cases death may be due to chance rather than to any inferiority in those which die first, yet we cannot possibly believe that this can be the case on the large scale on which nature works.