“There is a law universal in nature, tending to render every reproductive being the best possible suited to its condition that its kind, or organized matter, is susceptible of, which appears intended to model the physical and mental or instinctive powers to their highest perfection and to continue them so. This law sustains the lion in his strength, the hare in her swiftness, and the fox in his wiles. As nature, in all her modifications of life, has a power of increase far beyond what is needed to supply the place of what falls by Time's decay, those individuals who possess not the requisite strength, swiftness, hardihood, or cunning, fall prematurely without reproducing — either a prey to their natural devourers, or sinking under disease, generally induced by want of nourishment, their place being occupied by the more perfect of their own kind, who are pressing on the means of subsistence.”

“The Religion of Life” (1858)

Quote reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 364

Napoleon : In His Own Words (1916)

Source: La Vita Nuova (1293), Chapter XIV, lines 49–50 (tr. Barbara Reynolds)

Il n’y a point de droit naturel: ce mot n'est qu’une antique niaiserie... Avant la loi il n’y a de naturel que la force du lion, ou le besoin de l’être qui a faim, qui a froid, le besoin en un mot.
Vol. II, ch. XLIV
Variant translation: There is no such thing as natural law, the expression is nothing more than a silly anachronism … There is no such thing as right, except when there is a law to forbid a certain thing under pain of punishment. Before law existed, the only natural thing was the strength of the lion, or the need of a creature who was cold or hungry, to put it in one word, need.
As translated by Horace B. Samuel (1916)
Le Rouge et le Noir (The Red and the Black) (1830)

VIII, 35
Meditations (c. 121–180 AD), Book VIII

1840s, Essays: First Series (1841), Compensation
Context: The universe is represented in every one of its particles. Every thing in nature contains all the powers of nature. Every thing is made of one hidden stuff; as the naturalist sees one type under every metamorphosis, and regards a horse as a running man, a fish as a swimming man, a bird as a flying man, a tree as a rooted man. Each new form repeats not only the main character of the type, but part for part all the details, all the aims, furtherances, hindrances, energies, and whole system of every other. Every occupation, trade, art, transaction, is a compend of the world, and a correlative of every other. Each one is an entire emblem of human life; of its good and ill, its trials, its enemies, its course and its end. And each one must somehow accommodate the whole man, and recite all his destiny.
The world globes itself in a drop of dew.

General Conclusions, Part I : Containing Considerations addressed to Unbelievers and especially to Mr. Gibbon
An History of the Corruptions of Christianity (1782)
Context: That miracles are things in themselves possible, must be allowed so long as it is evident that there is in nature a power equal to the working of them. And certainly the power, principle, or being, by whatever name it be denominated, which produced the universe, and established the laws of it, is fully equal to any occasional departures from them. The object and use of those miracles on which the christian religion is founded, is also maintained to be consonant to the object and use of the general system of nature, viz. the production of happiness. We have nothing, therefore to do, but to examine, by the known rules of estimating the value of testimony whether there be reason to think that such miracles have been wrought, or whether the evidence of Christianity, or of the christian history, does not stand upon as good ground as that of any other history whatever.

Source: The Limits of Evolution, and Other Essays, Illustrating the Metaphysical Theory of Personal Ideaalism (1905), Human Immortality: its Positive Argument, p.310