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ties and bowed its grandeur to the pettiness of our perceiving that we might know it.
Aided most essentially by the light which the study of the living body has given him, the physicist has learnt to recognise, through all Nature, a perpetual series of activities of various modes. But there is one of these modes of action which is presented to us with a special emphasis in the organic worldnamely, the storing up of force and its liberation. In the animal body we give to this sequence the special name of nutrition and function, because in it the object attained by the liberation of the force is one of a utility obvious to us, and directly exciting our sympathies; but the process itself is of course by no means a specially animal or organic one. Through all Nature force is perpetually being stored up and given off, and results no less marked ensue. Though often destructive, they are often also of a service perfectly visible to us. Every electric discharge, the thunderstorm, the earthquake, the very light of the sun, and the rain are instances. In every sudden exhibition of energy we see it; and Nature is full of such sudden strokes, mingling with other forms of action to complete the sum of her perpetual change.
But in the world we term organic we see this process—the storing up and setting free of force—as it
were specialised, and imparting to it an emphatic character. The living structure is a structure containing force; it is as a bow drawn tense ; as a weight suspended. The fact that it contains force, ready for sudden exertion when a call arises, or for more continuous service in more constant processes, is at the same time one of its chief distinctions, and one of the characters which it possesses in common with many things that are not termed living. The organic world presents to us this special relation of force not as peculiar to itself indeed, yet with a unique and special prominence: so that it stands before us almost as if it were a part of Nature to which a special function had fallen. As we see the developing animal body putting forth various organs which carry to the utmost pitch each its peculiar function
-muscle for motion, nerves for conduction, and the rest-so we might well deem that in the whole organic world we saw before us an organ' of a mightier frame : an organ devoted, as to its special function, to the storing up of force to work ulterior ends.
The apparent distinctness of the organic world should be to us, if we judged consistently, a mark, not of the absence but of the presence of life in the great whole of which it forms a part. For life puts
forth special organs, and here is one--in the organic world. Doubtless there are more, when we shall have learnt to see them.
Thus it is that the student of medicine inevitably has for his study the whole realm of Nature. The tales of our ancestors tell us of a cup offered to Thor to drink. It seemed but a fair goblet, a few gallons, enough, perchance, to drown a man, such as he had often quaffed, and he took it laughingly; but for all his drinking the cup scarcely became emptier. It was the ocean that he drank. And to you also, gentlemen, is offered a cup, a fair-sized cup, just the knowledge of the human frame-a fair goblet for a thirsty soul. But drain it, drink your fill, exhaust your power; you will find it full as ever: it is the ocean you are drinking.
For if we look at the living body thus—see it as an exhibition of nutrition and function, or of force stored up and an action effected by its liberation—if we recognise that this process is the same in the organic body and in the inorganic world, we can understand why the study of the bodily life has drawn within its compass not only, on the one hand, that of all inorganic force, but, on the other, that of the whole conscious life of man. For in this conscious life we do but meet with the same process under another form. And though our time affords us space but for the
merest outline, I should like to make this, if I can, in some small degree clear to you, so greatly does it add to the interest of your chief study.
Suppose that on any subject we are studying we start with a false assumption, there is one way, and but one, in which we are cured. We have to take the trouble of tracing out the consequences of the false assumption, until, through the weight of their unreasonableness, we are compelled to let them go, and accept a different thought. Every reductio ad absurdum in our Euclid presents to us the process; there is an effort, a strain, a tension put upon the mind, and as it ceases the premiss is corrected. Force is stored up, and as it is set free a 'function' comes, which is the change in our fundamental thought.
Now, take the last great generalisation of science —that which, perhaps, more than any other, will make the scientific glory of the age just past-the unity of force. Is not the process of its attainment plainly that which I have described ?-a vast nutrition which had that new vision for its function. It came by a reductio ad absurdum. For man's senses gave him a false assumption to start with. They showed him, not the presence of one force, but the appearance of many-arbitrary, disjointed, beginning and ceasing. The electric flash passes and seems to be altogether gone; the wave dies on the shore, but the shore does not move. My mere will seems to me to move my arm, and when its motion is over there is an end.
What could men have done but what they did ?trace out (as they did with splendid exactitude and completeness) the result of examining Nature on the assumption of many separate forces. And they surrounded themselves accordingly with fictitious entities
-imponderable fluids and so on-without end. What a weight of suppositions they had to bear! But it fell at last (most happily for us); and the strain and tension of the mind found relief in the thought of a simple constancy of action appearing under various forms.
We recognise familiarly the identity of the raising of a weight with the nutrition of a muscle, and of the fall of the weight with the contraction of the muscle. But is not the parallel equally obvious in this living process of the mind ?—the toilsome raising of the weight of false hypothesis and its sudden fall, effecting a function not less distinct. A poet has seen this before. Listen to the words Shelley puts into the mouth of Prometheus :
Hark the rushing snow !