distinct from the natural induction which all men practise, is almost as much the creation of Bacon as deductive logic is that of Aristotle. It must, however, be acknowledged that the one left far more to be added and remodelled by his successors than did the other.
'Man,' says Bacon, 'is the servant and interpreter of nature.' But as the bare hand is of little use in mechanical work, so the unassisted intellect can effect little in the work of reasoning. The one requires instruments, the other rules. The rules supplied by the logic in vogue lend no aid in the examination of principles. He who takes the wrong road wanders the further from his goal, the further he goes. The syllogism is, from the very nature of the case, incompetent to prove the ultimate premisses from which it proceeds. The only hope, therefore, of those who wish to establish knowledge on a firm basis is in a logic which shall be competent to examine these higher generalisations or first principles from which the various sciences start, that is to say, in a true induction. Before, however, attempting to supply this want. Bacon lingers for a while over the existing condition of knowledge, points out the phantoms which obscure the vision of truth, enumerates the causes of past errors, and suggests grounds of hope for the future.
Perhaps the best known part of the 'Novum Organum,' certainly one of the most valuable parts, is the account of the 'Idola Mentis Humanæ,' or 'phantoms of the human mind,' which occupies Aphorisms 38-70 of Book i. These 'idols' (ёίδɯʎч, phantoms or spectres, and not, as they have sometimes been erroneously interpreted, false gods) are four in number, and are enumerated as 'idols of the tribe' (idola tribus), 'idols of the den' (idola specus), 'idols of the market-place' (idola fori), and 'idols of the theatre' (idola theatri). In number they happen to correspond with the 'offendicula' of Roger Bacon; namely, unworthy authority, custom, vulgar opinion, and concealment of ignorance combined with the ostentation of apparent wisdom. There is, however, little other resemblance between the 'idola' and the 'offendicula,' and Francis Bacon is probably in no way indebted to his elder namesake for this part of his doctrine.
'The idols of the tribe have their foundation in human nature itself, and in the very tribe or race of men.' ... 'The idols of the den have their origin in the peculiar constitution, mental or bodily, of each individual; and also in education, habit, and accident.' The idols of the market-place ('idola fori'),
which have insinuated themselves into the mind through the association of words and names with things, are. Bacon says, the most troublesome of all. They are of two kinds, being either names of supposed entities which have no real existence, or words inadequately or erroneously representing things or qualities actually existing. The idols of the theatre, so called because they succeed one another like the plays on a stage, arise either from false systems of philosophy or from perverse laws of demonstration.
The enumeration of the grounds of hope naturally includes many criticisms on the methods then in vogue, favourable auguries being drawn from the likelihood of their amelioration. Thus, in Aph. 104, where he protests against the prevalent habit of flying off at once from particular facts to first principles or the most general axioms of all, he insists on the importance of establishing by a carefid induction a sufficient number of intermediate axioms ('axiomata media'), which are 'the true and solid and living 'axioms, on which depend the affairs and fortunes of men.' Again, in Aph. 105, he emphatically condemns the method of induction by simple enumeration, or mere addition of instances. Then, after contrasting with this unscientific and faulty form the induction which he himself contemplates, he adds with a true appreciation of the difficulties of his task: 'But in order to furnish this induction or demonstration well and didy for its work, very many things are to be provided which have never yet entered the thoughts of any mortal man; insomuch that greater labour will have to be spent on it than has hitherto been spent on the syllogism.' It is in this new kind of induction that his chief hope lies.
In the concluding aphorisms of the first book, Bacon answers, by anticipation, the important question whether he intends his new method to be confined to the problems of natural philosophy, or contemplates its application to the other sciences as well, 'logic, ethics, and politics.' To this question he replies (Aph. 127): 'Now I certainly mean what I have said to be understood of them all; and as the common logic, which governs by the syllogism, extends not only to natural but to all sciences; so does mine also, which proceeds by induction, embrace everything. For I form a history and tables of discovery for anger, fear, shame, and the like; for matters political, and again for the mental operations of memory, affirmation and negation, judgment and the rest: not less than for heat and cold, or light, or vegetation, or the like.' This statement should
