* Morell's Hist. of Speculative Phil., p. 34, vol. 1. ** Mill, p. 165, vol. 1. *** T. W. Thornton: Reasoner No. 72, p. 664. **** Lamartine's Hist. Girondists, pp. 14-15, vol. 1. Familiarity with the characteristics of science imparts considerable power for the detection of fallacy. A logician is imperfect without scientific tastes and habits. The man of science has all his knowledge systematised and arranged. What other people have in confusion, he has in order. The elements of knowledge are, more or less, as has been observed, known to all men--but in their perfect, communicable, and usable state, they are-known only to the educated and scientific man. What training is to the soldier, science is to the thinker. It enables him to control all his resources and employ his natural powers to the best advantage. It is this which constitutes the superiority of the educated over the ignorant. Astronomy, navigation, architecture, geometry, political economy, morals, all rest, or should rest, and do rest, if they have-attained to the perfection of science, on primary facts and first principles. Every step can be measured by an axiom--every result can be traced to a first principle.* To detect error, then, in any province of investigation, or any domain of argument, the logician first looks to the primary principles on which it is based, and thus tests the legitimacy of its conclusions. As respects those who deal in things professedly above reason, It was well said by an anonymous writer of the old school of sturdy thinkers,--'Of such men as these I usually demand, whether their own assent to things they would have us believe, be grounded upon some _rational argument_. If they say 'tis not, they are fools to believe it themselves; and I should add to the number of fools, if, after this acknowledgment, I should believe them: but if they say it is, I desire them to produce their argument; for since 'tis framed by a human understanding, the force of it may also be comprehended and judged of by a human understanding: and tis to no purpose to say that the subject surpasses human reason: for if it do so indeed, it will surpass _theirs_ as well as _mine_, and so leave us both upon even terms. And let the thing assented to be what it will, the assent itself must be founded upon a _sufficient reason_, and consequently upon one that is _intelligible_ to the human intellect that is wrought on by it.'** * See Beauties and Uses of Euclid, chap. vi., Logic of Euclid. ** A Discourse on Things above Reason, 1681.