219. To make our meaning clear, let us suppose that two sportsmen go out hunting together, each with a good rifle and a good pocket chronometer. After a hard day’s work, the one turns to his companion and says:--“It is now six o’clock by my watch; we had better rest ourselves,” upon which the other looks at his watch, and he would be very much surprised and exceedingly indignant with the maker, if he did not find it six o’clock also. Their chronometers are evidently in the same state, and have been doing the same thing; but what about their rifles? Given the condition of the one rifle, is it possible by any refinement of calculation to deduce that of the other? We feel at once that the bare supposition is ridiculous. 220. It is thus apparent that, as regards energy, structures are of two kinds. In one of these, the object sought is regularity of action, and the means employed, a stable arrangement of natural forces: while in the other, the end sought is freedom of action, and a sudden transmutation of energy, the means employed being an unstable arrangement of natural forces. The one set of machines are characterized by their calculability--the other by their incalculability. The one set, when at work, are not easily put wrong, while the other set are characterized by great delicacy of construction. _An Animal is a delicately-constructed Machine._ 221. But perhaps the reader may object to our use of the rifle as an illustration. For although it is undoubtedly a delicately-constructed machine, yet a rifle does not represent the same surpassing delicacy as that, for instance, which characterizes an egg balanced on its longer axis. Even if at full cock, and with a hair trigger, we may be perfectly certain it will not go off of its own accord. Although its object is to produce a sudden and violent transmutation of energy, yet this requires to be preceded by the application of an amount of energy, however small, to the trigger, and if this be not spent upon the rifle, it will not go off. There is, no doubt, delicacy of construction, but this has not risen to the height of incalculability, and it is only when in the hands of the sportsman that it becomes a machine upon the condition of which we cannot calculate. Now, in making this remark, we define the position of the sportsman himself in the Universe of Energy. The rifle is delicately constructed, but not surpassingly so; but sportsman and rifle, together, form a machine of surpassing delicacy, _ergo_ the sportsman himself is such a machine. We thus begin to perceive that a human being, or indeed an animal of any kind, is in truth a machine of a delicacy that is practically infinite, the condition or motions of which we are utterly unable to predict. In truth, is there not a transparent absurdity in the very thought that a man may become able to calculate his own movements, or even those of his fellow? _Life is like the Commander of an Army._