THREE:A cubic inch of water, by taking up a given amount of heat, is expanded to more than five hundred cubic inches of steam, at a pressure of forty-five pounds to the square inch. This extraordinary expansion, if performed in a close vessel, would exert a power five hundred times as great as would be required to force the same quantity of water into the vessel against this expansive pressure; in other words, the volume of the water when put into the vessel would be but one five-hundredth part of its volume when it is allowed to escape, and this expansion, when confined in a steam-boiler, exerts the force that is called steam-power. This force or power is, through the means of the engine and its details, communicated and applied to different kinds of work where force and movement are required. The water [33] employed to generate steam, like the engine and the boiler, is merely an agent through which the energy of heat is applied.Such arguments have almost the air of an afterthought, and Plato was perhaps more powerfully swayed by other considerations, which we shall now proceed to analyse. When pleasure was assumed to be the highest good, knowledge was agreed to be the indispensable means for its attainment; and, as so often happens, the means gradually substituted itself for the end. Nor was this all; for knowledge (or reason) being not only the means but the supreme arbiter, when called on to adjudicate between conflicting claims, would naturally pronounce in its own favour. Naturally, also, a moralist who made science the chief interest of his own life would come to believe that it was the proper object of all227 life, whether attended or not by any pleasurable emotion. And so, in direct opposition to the utilitarian theory, Plato declares at last that to brave a lesser pain in order to escape from a greater, or to renounce a lesser pleasure in order to secure a greater, is cowardice and intemperance in disguise; and that wisdom, which he had formerly regarded as a means to other ends, is the one end for which everything else should be exchanged.139 Perhaps it may have strengthened him in this attitude to observe that the many, whose opinion he so thoroughly despised, made pleasure their aim in life, while the fastidious few preferred knowledge. Yet, after a time, even the latter alternative failed to satisfy his restless spirit. For the conception of knowledge resolved itself into the deeper conceptions of a knowing subject and a known object, the soul and the universe, each of which became in turn the supreme ideal. What interpretation should be given to virtue depended on the choice between them. According to the one view it was a purification of the higher principle within us from material wants and passions. Sensual gratifications should be avoided, because they tend to degrade and pollute the soul. Death should be fearlessly encountered, because it will release her from the restrictions of bodily existence. But Plato had too strong a grasp on the realities of life to remain satisfied with a purely ascetic morality. Knowledge, on the objective side, brought him into relation with an organised universe where each individual existed, not for his own sake but for the sake of the whole, to fulfil a definite function in the system of which he formed a part. And if from one point of view the soul herself was an absolutely simple indivisible substance, from another point of view she reflected the external order, and only fulfilled the law of her being when each separate faculty was exercised within its appropriate sphere.
