s. The _idola
tribus_, finally, are grounded in the nature of the human species. To this
class belong, among others, illusions of the senses, which may in part be
corrected by the use of instruments, with which we arm our organs; further,
the tendency to hold fast to opinions acceptable to us in spite of contrary
instances; similarly, the tendency to anthropomorphic views, including,
as its most important special instance, the mistake of thinking that we
perceive purposive relations everywhere and the working of final causes,
after the analogy of human action, when in reality efficient causes alone
are concerned. Here Bacon's injunction runs, not to interpret natural
phenomena teleologically, but to explain them from mechanical causes; not
to narrow the world down to the limits of the mind, but to extend the mind
to the boundaries of the world, so that it shall understand it as it
really is.

To these warnings there are added positive rules. When the investigator,
after the removal of prejudices and habitual modes of thought, approaches
experience with his senses unperverted and a purified mind, he is to
advance from the phenomena given to their conditions. First of all, the
facts must be established by observation and experiment, and systematically
arranged,[1] then let him go on to causes and laws.[2] The true or
scientific induction[3] thus inculcated is quite different from the
credulous induction of common life or the unmethodical induction of
Aristotle. Bacon emphasizes the fact that hitherto the importance of
negative instances, which are to be employed as a kind of counter-proof,
has been completely overlooked, and that a substitute for complete
induction, which is never attainable, may be found, on the one hand, in the
collection of as many cases as possible, and, on the other, by considering
the more important or decisive cases, the "prerogative instances." Then the
inductive ascent from experiment to axiom is to be followed by a deductive
descent from axioms to new experiments and discoveries. Bacon rejects
the syllogism on the ground that it fits one to overcome his opponent in
disputation, but not to gain an active conquest over nature. In his own
application of these principles of method, his procedure was that of a
dilettante; the patient, assiduous labor demanded for the successful
promotion of the mission of natural investigation was not his forte. His
strength lay in the postulation of problems, the sti