§. 3. Another reason is the imposture and fallacy of our senses, which impose not only on common heads, who scarce at all live to the higher principle; but even more refined Mercuries, who have the advantages of an improved reason to disabuse them, are yet frequently captivated to these deceiving prepossessions: appealing to a judicature both uncommissioned and unjust; and when the clearest truth is to be tried by such judges, its innocence will not secure it from the condemning award of that unintelligent tribunal: for since we live the life of brutes, before we grow into man; and our understandings in this their nonage, being almost merely passive to sensible impressions, receiving all things in an uncontroverted and promiscuous admission: it cannot be, that our knowledge should be other, than an heap of misconception and error, and conceits as impertinent as the toys we delight in. All this while we have no more reason, than the ΕΙΔΩΛΟΝ ΨΥΧΗΣ [Greek: EIDOLON PSYCHES](as Plotinus calls it) amounts to. And besides this our easy submission to sophistications of sense, and inability to prevent the miscariages of our junior reasons; and that which strikes the great stroke toward our after-deceptions, is the pertinacious adherence of many of these first impressions, to our advanced understandings. That which is early received, if in any considerable strength of imfiress, as it were grows into our tender natures, and is therefore of difficult remove. Thus a fright in minority, or an antipathy then contracted, is not worn out but with its subject. And it may be more than a story, that Nero derived much of his cruelty from the nurse that suckled him. Now though our coming judgements do in part undeceive us, and rectify the grosser errors which our unwary sensitive hath engaged us in; yet others are so fleshed in us, that they maintain their interest upon the deceptibility of our decayed natures, and are cherished there, as the legitimate issues of our reasonable faculties.
Indeed sense itself detects its more palpable deceits, by a counter-evidence; and the more ordinary impostures seldom outlive the first experiments. If our sight represent a staff as crooked in the water; the same faculty rectifies both it, and us, in the thinner element. And if a square tower seem round at a distance; the eye, which mistook in the circumstance of its figure, at that remove, corrects the mistake in a due approach: yea, and befriends those who have learned to make the advantage of its informations, in more remote and difficil discoveries. And though his sense occasion the careless rustic to judge the sun no bigger than a cheese-fat; yet sense too by a frugal improvement of its evidence, grounds the astronomers knowledge, that it's bigger than this globe of earth and water. Which it doth not only by the advantageous assistance of a tube, but by less industrious experiments, showing in what degrees distance minorates the object. But yet in infinite other cases, wherein sense can afford none, or but very little help to disintangle us; our first deceptions lose no ground, but rather improve in our riper years: so that we are not weaned from our childhood, till we return to our second infancy; and even our grey heads outgrow not those errors, which we have learned before the alphabet.
Thus our reasons being inoculated on sense, will retain a relish of the stock they grew on: and if we would endeavour after an unmixed knowledge; we must unlive our former lives, and (inverting the practice of Penelope) undo in the day of our more advanced understandings, what we had spun in the night of our infant-ignorance. He that would rebuild a decayed structure, must first pluck down the former ruins. A fabric, though high and beautiful, if founded on rubbish, is easily made the triumph of the winds: and the most pompous seeming knowledge, that's built on the unexamined prejudices of sense, stands not, but till the storm ariseth; the next strong encounter discovers its weakness, in a shameful over-throw. Since then, a great part of our scientifical treasure is most likely to be adulterate, though all bears the image and superscription of truth; the only way to know what is sophisticate, and what is not so, is to bring all to the examen of the touchstone: for the prepossessions of sense having (as is showen) so mingled themselves with our genuine truths, and being as plausible to appearance as they, we cannot gain a true assurance of any, but by suspending our assent from all, till the deserts of each, discovered by a strict enquiry, claim it. Upon this account I think the method of the most excellent Descartes not unworthy its author; and (since dogmatical ignorance will call it so) a skepticism, that's the only way to science. But yet this is so difficult in the impartial and exact performance, that it may be well reckoned among the bare possibilities, which never commence into a futurity: it requiring such a free, sedate, and intent minde, as it may be is nowhere found but among the Platonical ideas. Do what we can, prejudices will creep in, and hinder our intellectual perfection: and though by this means we may get some comfortable allay to our distempers; yet can it not perfectly cure us of a disease, that sticks as close to us as our natures.