THREE:The cause which first arrested and finally destroyed the free movement of Greek thought was not any intrinsic limitation or corruption of the Greek genius, but the ever-increasing preponderance of two interests, both tending, although in different ways and different degrees, to strengthen the principle of authority and to enfeeble the principle of reason. One was the theological interest, the other was the scholastic interest. The former was the more conspicuous and the more mischievous of the two. From the persecution of Anaxagoras to the prohibition of philosophical teaching by Justinian, we may trace the rise and spread of a reaction towards superstition, sometimes advancing and sometimes receding, but, on the whole, gaining ground from age to age, until from the noontide splendour of Pericles we pass to that long night which stretches in almost impenetrable darkness down to the red and stormy daybreak of the Crusades. And it was a reaction which extended through all classes, including the philosophers themselves. It seems to me that where the Athenian school, from Socrates on, fall short of their predecessors, as in some points they unquestionably do, their inferiority is largely due to this cause. Its influence is very perceptible in weakening the speculative energies of thosexii who stand at the greatest distance from the popular beliefs. It was because dislike for theology occupied so large a place in the thoughts of Epicurus and his disciples, that they valued science only as a refutation of its teaching, instead of regarding it simply as an obstacle to be removed from the path of enquiry. More than this; they became infected with the spirit of that against which they fought, and their absolute indifference to truth was the shadow which it cast on their minds.I now come to speak directly of the present work and its objects. It may be claimed that a book can go no further in treating of mechanical manipulation than principles or rules will reach, and that books must of necessity be confined to what may be called generalities. This is in a sense true, and it is, indeed, a most difficult matter to treat of machine operations and shop processes; but the reason is that machine operations and shop processes have not been reduced to principles or treated in the same way as strains, proportions, the properties of material, and so on. I do not claim that manipulative processes can be so generalisedthis would be impossible; yet much can be done, and many things regarded as matters of special knowledge can be presented in a way to come within principles, and thus rendered capable of logical investigation.
He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections
