The human species

by A. de Quatrefages

Others consider living beings as the result of a cause entirely different from those which act in inanimate bodies, and refer to this cause alone everything which takes place in these beings.

These two methods appear to me, from the exclusive element in each, to be equally ill-founded. It cannot be denied that phenomena identical with those characteristic of inanimate bodies are found in organised beings, and we have, therefore, no scientific reason to attribute them to different causes.

But organised beings have also their special phenomena radically distinct from, or even opposed to, the former. Is it possible to refer all of them to one, or to several, identical causes? I think not. For this reason, I admit with a great number of eminent men of every age and country, and, I believe, with the majority of those that respect modern science, that organised beings owe their distinctive characteristics to a Special Cause, to a Special Force, to Life, which in them is associated with the inorganic forces. For this reason I consider it legitimate to call them Living Beings.

I shall often, however, return to this class of considerations, in order to make it quite clear in what sense I take these words, Force, and Life.

III. The two Empires of Pallas are themselves sub-divided into Kingdoms, which are characterised by special facts and phenomena, becoming more and more complicated as we ascend the scale of nature.

And, in the first place, I distinctly admit with de Candolle the existence of a Sidereal Kingdom. To any one who considers, as far as we are able, the little that we know of the universe, the celestial bodies, suns, planets, and comets or satellites only appear as molecules of the great All which fills indefinite Space. One general phenomenon which is unchangeable, however varied in its forms, is, as it were, the attribute of these bodies. All, whether gaseous or solid, obscure or luminous, hot or cold, move within curves of the same nature, obeying the laws discovered by Kepler. It is now well known that fixed stars do not exist.

In order to explain this phenomenon philosophers have admitted the existence of a force which they have called Gravitation, the effect of which is to precipitate the stars towards one another, as if they mutually attracted each other, whilst obeying the laws of Newton. Now it is well known that the great Englishman himself gave no opinion upon the mode of action of this force, and that he hesitated between the hypothesis of Attraction and that of Impulsion. The first should prevail as being more in accordance with the immediate results of observation; but the second also has had serious partisans, among whom I will only mention M. de Tessan.

Thus Newton, in spite of all his genius, cannot tell us what was the cause of the movement of the stars; he was not even able to determine the immediate mode of action of this cause; and yet there is not a scientific term more universally received than that of Gravitation, there is not a case in which the expression Force is more generally accepted. The reason of this is, that in the presence of general facts and groups of phenomena, it is necessary to make use of terms as simple as possible. We must, however, avoid the delusion of thinking that naming is equivalent to explaining.

In cases analogous to that of which we have been treating, the word Force merely indicates the presence of an Unknown Cause, which gives rise to a group of fixed phenomena. In assigning names to each of the Forces or Unknown Causes to which we consider ourselves able to refer certain groups of phenomena, we facilitate the demonstration and discussion of the facts. The scientific man knows very well that he cannot go beyond this.