The tenacity of life

March 22.

Every organism, whether animal or vegetable, is contending for the possession of the planet. This suggests an immense and wonderful greediness and tenacity of life  as if each species is bent on taking entire possession of the globe wherever the climate and soil will permit.

Nature opposes to this many obstacles, as climate, myriads of brute and also human foes, and of competitors which may preoccupy the ground. And each species prevails as much as it does, because of the ample preparations it has made for the contest,- it has secured a myriad chances.

It is true we do not know whether one or many plants of a given kind were originally created, but I think it is the most reasonable and simple to suppose that only one was, -- to suppose as little departure as possible from the existing order of things. They spread themselves by whatever means they possessed as far as they could, and they are still doing so, naturalizing themselves in one or the other country. This is more philosophical than to suppose that they were independently created in each.

H. D. Thoreau, Journal, March 22, 1861

There is an immense and wonderful tenacity of life.

Consider how soon some plants that spread rapidly by seeds or roots would cover an area equal to the surface of the globe, how soon some species of trees would equal in mass the earth itself, if all their seeds became full grown trees; and how soon some fishes would fill the ocean, if all their ova became full-grown fishes,.

We are tempted to say that every organism, whether animal or vegetable, is contending for the possession of the planet, and, if any one were sufficiently favored it would at length convert the entire mass of the globe into its own substance.

When we consider how soon some plants which spread rapidly, by seeds or roots, would cover an area equal to the surface of the globe, how soon some species of trees, as the white willow, for instance, would equal in mass the earth itself, if all their seeds became full- grown trees, how soon some fishes would fill the ocean if all their ova became full-grown fishes, we are tempted to say that every organism, whether animal or vegetable, is contending for the possession of the planet, and, if any one were sufficiently favored, supposing it still possible to grow, as at first, it would at length convert the entire mass of the globe into its own substance. 

Nature opposes to this many obstacles, as climate, myriads of brute and also human foes, and of competitors which may preoccupy the ground. Each suggests an immense and wonderful greediness and tenacity of life ( I speak of the species, not individual ), as if bent on taking entire possession of the globe wherever the climate and soil will permit. And each prevails as much as it does, because of the ample preparations it has made for the contest,  – it has secured a myriad chances, – because it never depends on spontaneous generation to save it .