But since the minds of men are strangely possessed and beset, so that there is no true and even surface left to reflect the genuine rays of things, it is necessary to seek a remedy for this also.
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.