Now the idols, or phantoms, by which the mind is occupied are either adventitious or innate.  The adventitious come into the mind from without; namely, either from the doctrines and sects of philosophers, or from perverse rules of demonstration.  But the innate are inherent in the very nature of the intellect, which is far more prone to error than the sense is.  For let men please themselves as they will in admiring and almost adoring the human mind, this is certain:  that as an uneven mirror distorts the rays of objects according to its own figure and section, so the mind, when it receives impressions of objects through the sense, cannot be trusted to report them truly, but in forming its notions mixes up its own nature with the nature of things.

And as the first two kinds of idols are hard to eradicate, so idols of this last kind cannot be eradicated at all.  All that can be done is to point them out, so that this insidious action of the mind may be marked and reproved (else as fast as old errors are destroyed new ones will spring up out of the ill complexion of the mind itself, and so we shall have but a change or errors, and not a clearance); and to lay it down once for all as a fixed and established maxim, that the intellect is not qualified to judge except by means of induction, and induction in its legitimate form.  This doctrine then of the expurgation of the intellect to qualify it for dealing with truth, is comprised in three refutations:  the refutation of the Philosophies; the refutation of the Demonstrations; and the refutation of the Natural Human Reason.  The explanation of which things, and of the true relation between the nature of things and the nature of the mind, is as the strewing and decoration of the bridal chamber of the Mind and the Universe, the Divine Goodness assisting; out of which marriage let us hope (and be this the prayer of the bridal song) there may spring helps to man, and a line and race of inventions that may in some degree subdue and overcome the necessities and miseries of humanity.  This is the second part of the work.

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But I design not only to indicate and mark out the ways, but also to enter them.  And therefore the third part of the work embraces the Phenomena of the Universe; that is to say, experience of every kind, and such a natural history as may serve for a foundation to build philosophy upon.  For a good method of demonstration or form of interpreting nature may keep the mind from going astray or stumbling, but it is not any excellence of method that can supply it with the material of knowledge.  Those however who aspire not to guess and divine, but to discover and know; who propose not to devise mimic and fabulous worlds of their own, but to examine and dissect the nature of this very world itself; must go to facts themselves for everything.  Nor can the place of this labour and search and worldwide perambulation be supplied by any genius or meditation or argumentation; no, not if all men’s wits could meet in one.  This therefore we must have, or the business must be for ever abandoned.  But up to this day such has been the condition of men in this matter, that it is no wonder if nature will not give herself into their hands.