To which let me here add another near of kin to this,at least in name,and that is letting the mind upon the suggestion of any new notion run immediately after similes to make it the clearer to itself;which,though it man be a good way and useful in the explaining our thoughts to others,yet it is by no means a right method to settle true notions of anything in ourselves,because similes always fail in some part and come short of that exactness which our conceptions should have to things,if we would think aright.This indeed makes men plausible talkers;for those are always most acceptable in discourse who have the was to let in their thoughts into other men's minds with the greatest ease and facility whether those thoughts are well formed and correspond with things matters not;few men care to be instructed but at an easy rate.They who in their discourse strike the fancy and take the hearers'conceptions along with them as fast as their words flow,are the applauded talkers and go for the only men of clear thoughts.
Nothing contributes so much to this as similes,whereby men think this themselves understand better because they are the better understood.But it is one thing to think right and another thing to know the right way to lay our thoughts before others with advantage and clearness,be they right or wrong.Well chosen similes,metaphors and allegories,with method and order,do this the best of anything,because,being taken from objects already known and familiar to the understanding,they are conceived as fast as spoken;and the correspondence being concluded,the thing they are brought to explain and elucidate is thought to be understood too.
Thus fancy passes for knowledge,and what is prettily said is mistaken for solid.
I say not this to decry metaphor,or with design to take away that ornament of speech;my business here is not with rhetoricians and orators,but with philosophers and lovers of truth;to whom I would beg leave to give this one rule whereby to try whether,in the application of their thoughts to anything for the improvement of their knowledge,they do in truth comprehend the matter before them really such as it is in itself.The way to discover this is to observe whether,in the laying it before themselves or others,they make use only of borrowed representations and ideas foreign to the thing,which are applied to it by way of accommodation,as bearing some proportion or imagined likeness to the subject under consideration.Figured and metaphorical expressions do well to illustrate more abstruse and unfamiliar ideas which the mind is not yet thoroughly accustomed to;but then they must be made use of to illustrate ideas that we already have,not to paint to us those which we yet have not.
Such borrowed and allusive ideas may follow real and solid truth,to set it off when found,but must by no means be set in its place and taken for it.If all our search has yet reached no further than simile and metaphor,we may assure ourselves we rather fancy than know and are not yet penetrated into the inside and reality of the thing,be it what it will,but content ourselves with what our imaginations,not things themselves,furnish us with.