* * * * *
Previously to the submitting my own ideas on the subject of life, and the powers into which it resolves itself, or rather in which it is manifested to us, I have hazarded this apparent digression from the anxiety to preclude certain suspicions, which the subject itself is so fitted to awaken, and while I anticipate the charges, to plead in answer to each a full and unequivocal—not guilty!
In the first place, therefore, I distinctly disclaim all intention of explaining life into an occult quality; and retort the charge on those who can satisfy themselves with defining it as the peculiar power by which death is resisted.
Secondly. Convinced—by revelation, by the consenting authority of all countries, and of all ages, by the imperative voice of my own conscience, and by that wide chasm between man and the noblest animals of the brute creation, which no perceivable or conceivable difference of organization is sufficient to overbridge—that I have a rational and responsible soul, I think far too reverentially of the same to degrade it into an hypothesis, and cannot be blind to the contradiction I must incur, if I assign that soul which I believe to constitute the peculiar nature of man as the cause of functions and properties, which man possesses in common with the oyster and the mushroom.[4]
Thirdly, while I disclaim the error of Stahl in deriving the phenomena of life from the unconscious actions of the rational soul, I repel with still greater earnestness the assertion and even the supposition that the functions are the offspring of the structure, and “Life[5] the result of organization,” connected with it as effect with cause. Nay, the position seems to me little less strange, than as if a man should say, that building with all the included handicraft, of plastering, sawing, planing, &c. were the offspring of the house; and that the mason and carpenter were the result of a suite of chambers, with the passages and staircases that lead to them. To make A the offspring of B, when the very existence of B as B presupposes the existence of A, is preposterous in the literal sense of the word, and a consummate instance of the hysteron proteron in logic. But if I reject the organ as the cause of that, of which it is the organ, though I might admit it among the conditions of its actual functions; for the same reason, I must reject fluids and ethers of all kinds, magnetical, electrical, and universal, to whatever quintessential thinness they may be treble distilled, and (as it were) super-substantiated. With these, I abjure likewise all chemical agencies, compositions, and decompositions, were it only that as stimulants they suppose a stimulability sui generis, which is but another paraphrase [pg 035] for life. Or if they are themselves at once both the excitant and the excitability, I miss the connecting link between this imaginary ether and the visible body, which then becomes no otherwise distinguished from inanimate matter, than by its juxtaposition in mere space, with an heterogeneous inmate, the cycle of whose actions revolves within itself. Besides which I should think that I was confounding metaphors and realities most absurdly, if I imagined that I had a greater insight into the meaning and possibility of a living alcohol, than of a living quicksilver. In short, visible surface and power of any kind, much more the power of life, are ideas which the very forms of the human understanding make it impossible to identify. But whether the powers which manifest themselves to us under certain conditions in the forms of electricity, or chemical attraction, have any analogy to the power which manifests itself in growth and organization, is altogether a different question, and demands altogether a different chain of reasoning: if it be indeed a tree of knowledge, it will be known by its fruits, and these will depends not on the mere assertion, but on the inductions by which the position is supported, and by the additions which it makes to our insight into the nature of the facts it is meant to illustrate.
To account for Life is one thing; to explain Life another. In the first we are supposed to state something prior (if not in time, yet in the order of Nature) to the thing accounted for, as the ground or cause of that thing, or (which comprises the meaning and force of both words) as its sufficient cause, quae et facit, et subest. And to this, in the question of Life, I know no possible answer, but GOD. To account for a thing is to see into the [pg 036] principle of its possibility, and from that principle to evolve its being. Thus the mathematician demonstrates the truths of geometry by constructing them. It is an admirable remark of Joh. Bapt. a Vico, in a Tract published at Naples, 1710,[6] “Geometrica ideò demonstramus, quia facimus; physica si demonstrare possimus, faceremus. Metaphysici veri claritas eadem ac lucis, quam non nisi per opaca cognoscimus; nam non lucem sed lucidas res videmus. Physica sunt opaca, nempe formata et finita, in quibus Metaphysici veri lumen videmus.” The reasoner who assigns structure or organization as the antecedent of Life, who names the former a cause, and the latter its effect, he it is who pretends to account for life. Now Euclid would, with great right, demand of such a philosopher to make Life; in the same sense, I mean, in which Euclid makes an Icosahedron, or a figure of twenty sides, namely, in the understanding or by an intellectual construction. An argument which, of itself, is sufficient to prove the untenable nature of Materialism.
To explain a power, on the other hand, is (the power itself being assumed, though not comprehended, ut qui datur, non intelligitur) to unfold or spread it out: ex implicito planum facere. In the present instance, such an explanation would consist in the reduction of the idea of Life to its simplest and most comprehensive form or mode of action; that is, to some characteristic instinct or tendency, evident in all its manifestations, and involved in the idea itself. This assumed as existing in kind, it will be required to present an ascending series of corresponding [pg 037] phenomena as involved in, proceeding from, and so far therefore explained by, the supposition of its progressive intensity and of the gradual enlargement of its sphere, the necessity of which again must be contained in the idea of the tendency itself. In other words, the tendency having been given in kind, it is required to render the phenomena intelligible as its different degrees and modifications. Still more perfect will the explanation be, should the necessity of this progression and of these ascending gradations be contained in the assumed idea of life, as thus defined by the general form and common purport of all its various tendencies. This done, we have only to add the conditions common to all its phenomena, and, those appropriate to each place and rank, in the scale of ascent, and then proceed to determine the primary and constitutive forms, i.e. the elementary powers in which this tendency realizes itself under different degrees and conditions.[7]
What is Life? Were such a question proposed, we should be tempted to answer, what is not Life that really is? Our reason convinces us that the quantities of things, taken abstractedly as quantity, exist only in the relations they bear to the percipient; in plainer words, they exist [pg 039] only in our minds, ut quorum esse est percipi. For if the definite quantities have a ground, and therefore a reality, in the external world, and independent of the mind that perceives them, this ground is ipso facto a quality; the very etymon of this world showing that a quality, not taken in its own nature but in relation to another thing, is to be defined causa sufficiens, entia, de quibus loquimur; esse talia, qualia sunt. Either the quantities perceived exist only in the perception, or they have likewise a real existence. In the former case, the quality (the word is here used in an active sense) that determines them belongs to Life, per ipsam hypothesin; and in the other case, since by the agreement of all parties Life may exist in other forms than those of consciousness, or even of sensibility, the onus probandi falls on those who assert of any quality that it is not Life. For the analogy of all that we know is clearly in favour of the contrary supposition, and if a man would analyse the meaning of his own words, and carefully distinguish his perceptions and sensations from the external cause exciting them, and at the same time from the quantity or superficies under which that cause is acting, he would instantly find himself, if we mistake not, involuntarily identifying the ideas of Quality and Life. Life, it is admitted on all hands, does not necessarily imply consciousness or sensibility; and we, for our parts, cannot see that the irritability which metals manifest to galvanism, can be more remote from that which may be supposed to exist in the tribe of lichens, or in the helvellæ, pezizee, &c., than the latter is from the phenomena of excitability in the human body, whatever name it may be called by, or in [pg 040] whatever way it may modify itself.[8] That the mere act of growth does not constitute the idea of Life, or the absence of that act exclude it, we have a proof in every egg before it is placed under the hen, and in every grain of corn before it is put into the soil. All that could be deduced by fair reasoning would amount to this only, that the life of metals, as the power which effects and determines their comparative cohesion, ductility, &c., was yet lower on the scale than the Life which produces the first attempts of organization, in the almost shapeless tremella, or in such fungi as grow in the dark recesses of the mine.
* * * * *
If it were asked, to what purpose or with what view we should generalize the idea of Life thus broadly, I should not hesitate to reply that, were there no other use conceivable, there would be some advantage in merely destroying an arbitrary assumption in natural philosophy, and in reminding the physiologists that they could not hear the life of metals asserted with a more contemptuous surprise than they themselves incur from the vulgar, when they speak of the Life in mould or mucor. But this is not the case. This wider view not only precludes a groundless assumption, it likewise fills up the arbitrary chasm between physics and physiology, and justifies us in using the former as means of insight into the latter, which would be contrary to all sound rules of ratiocination if the powers working in the objects of the two sciences were absolutely [pg 041] and essentially diverse. For as to abstract the idea of kind from that of degrees, which are alone designated in the language of common use, is the first and indispensable step in philosophy, so are we the better enabled to form a notion of the kind, the lower the degree, and the simpler the form is in which it appears to us. We study the complex in the simple; and only from the intuition of the lower can we safely proceed to the intellection of the higher degrees. The only danger lies in the leaping from low to high, with the neglect of the intervening gradations. But the same error would introduce discord into the gamut, et ab abusu contra usum non valet consequentia. That these degrees will themselves bring forth secondary kinds sufficiently distinct for all the purposes of science, and even for common sense, will be seen in the course of this inquisition: for this is one proof of the essential vitality of nature, that she does not ascend as links in a suspended chain, but as the steps in a ladder; or rather she at one and the same time ascends as by a climax, and expands as the concentric circles on the lake from the point to which the stone in its fall had given the first impulse. At all events, a contemptuous rejection of this mode of reasoning would come with an ill grace from a medical philosopher, who cannot combine any three phenomena of health or of disease without the assumption of powers, which he is compelled to deduce without being able to demonstrate; nay, even of material substances as the vehicles of these powers, which he can never expect to exhibit before the senses.