ONE:Drawings represent and explain the machinery to which they relate as the symbols in algebra represent quantities, and in a degree admit of the same modifications and experiments to which the machinery itself could be subjected if it were already constructed. Drawings are also an important aid in developing designs or conceptions. It is impossible to conceive of, and retain in the mind, all the parts of a complicated machine, and their relation to each other, without some aid to fix the various ideas as they arise, and keep them in sight for comparison; like compiling statistics, the footings must be kept at hand for reference, and to determine the relation that one thing may bear to another.
THREE:Pyrrho, who probably no more believed in books than in anything else, never committed his opinions to writing; and what we know of them is derived from the reports of his disciples, which, again, are only preserved in a very incomplete form by the compilers of the empire. According to these, Pyrrho began by declaring that the philosophic problem might be summed up in the three following questions:138 What is the nature of things? What should be our relation to them? What is the practical consequence of this determination? Of its kind, this statement is probably the best ever framed, and might be accepted with equal readiness by every school of thought. But the scepticism of Pyrrho at once reveals itself in his answer to the first question. We know nothing about things in themselves. Every assertion made respecting them is liable to be contradicted, and neither of the two opposing propositions deserves more credence than the other. The considerations by which Pyrrho attempts to establish this proposition were probably suggested by the systems of Plato and Aristotle. The only possible avenues of communication with the external world are, he tells us, sense and reason. Of these the former was so universally discredited that he seems to have regarded any elaborate refutation of its claims as superfluous. What we perceive by our senses is the appearance, not the reality of things. This is exactly what the Cyrenaics had already maintained. The inadequacy of reason is proved by a more original method. Had men any settled principles of judgment, they would agree on questions of conduct, for it is with regard to these that they are best informed, whereas the great variety of laws and customs shows that the exact opposite is true. They are more hopelessly divided on points of morality than on any other.227 It will be remembered that Pyrrhos fellow-townsman, Hippias, had, about a hundred years earlier, founded his theory of Natural Law on the arbitrary and variable character of custom. The result of combining his principles with those professed by Protagoras and Gorgias was to establish complete moral scepticism; but it would be a mistake to suppose that moral distinctions had no value for him personally, or that they were neglected in his public teaching.
THREE:Nor was this all. Thought, after having, as it would seem, wandered away from reality in search of empty abstractions, by the help of those very abstractions regained possession of concrete existence, and acquired a far fuller intelligence of its complex manifestations. For, each individual character is an assemblage of qualities, and can only be understood when those qualities, after having been separately studied, are finally recombined. Thus, biography is a very late production of literature, and although biographies are the favourite reading of those who most despise philosophy, they could never have been written without its help. Moreover, before characters can be described they must exist. Now, it is partly philosophy which calls character into existence by sedulous inculcation of self-knowledge and self-culture, by consolidating a mans individuality into something independent of circumstances, so that it comes to form, not a figure in bas-relief, but what sculptors call a figure in the round. Such was Socrates himself, and such were the figures which he taught Xenophon and Plato to recognise and portray. Character-drawing begins with them, and the Memorabilia in particular is the earliest attempt at a biographical analysis that we possess. From this to Plutarchs Lives there was still a long journey to be accomplished, but the interval between them is less considerable than that which divides Xenophon from his immediate predecessor, Thucydides. And when we remember how intimately the substance of Christian teaching is connected with the literary form of its first record, we shall still better appreciate the all-penetrating influence of Hellenic thought,158 vying, as it does, with the forces of nature in subtlety and universal diffusion.
THREE:6Milling, as explained, being a more rapid process than either planing or turning, it seems strange that so few machines of this kind are employed in engineering shops. This points to some difficulty to be contended with in milling, which is not altogether apparent, because economic reasons would long ago have led to a more extended use of milling processes, if the results were as profitable as the speed of cutting indicates. This is, however, not the case, except on certain kinds of material, and only for certain kinds of work.
