By this imposition of names,some of larger,some of stricter signification,we turn the reckoning of the consequences of things imagined in the mind into a reckoning of the consequences of appellations.For example,a man that hath no use of speech at all,(such as is born and remains perfectly deaf and dumb),if he set before his eyes a triangle,and by it two right angles (such as are the corners of a square figure),he may by meditation compare and find that the three angles of that triangle are equal to those two right angles that stand by it.But if another triangle be shown him different in shape from the former,he cannot know without a new labour whether the three angles of that also be equal to the same.But he that hath the use of words,when he observes that such equality was consequent,not to the length of the sides,nor to any other particular thing in his triangle;but only to this,that the sides were straight,and the angles three,and that that was all,for which he named it a triangle;will boldly conclude universally that such equality of angles is in all triangles whatsoever,and register his invention in these general terms:Every triangle hath its three angles equal to two right angles.And thus the consequence found in one particular comes to be registered and remembered as a universal rule;and discharges our mental reckoning of time and place,and delivers us from all labour of the mind,saving the first;and makes that which was found true here,and now,to be true in all times and places.
But the use of words in registering our thoughts is in nothing so evident as in numbering.A natural fool that could never learn by heart the order of numeral words,as one,two,and three,may observe every stroke of the clock,and nod to it,or say one,one,one,but can never know what hour it strikes.And it seems there was a time when those names of number were not in use;and men were fain to apply their fingers of one or both hands to those things they desired to keep account of;and that thence it proceeded that now our numeral words are but ten,in any nation,and in some but five,and then they begin again.And he that can tell ten,if he recite them out of order,will lose himself,and not know when he has done:much less will he be able to add,and subtract,and perform all other operations of arithmetic.So that without words there is no possibility of reckoning of numbers;much less of magnitudes,of swiftness,of force,and other things,the reckonings whereof are necessary to the being or well-being of mankind.
When two names are joined together into a consequence,or affirmation,as thus,A man is a living creature;or thus,If he be a man,he is a living creature;if the latter name living creature signify all that the former name man signifieth,then the affirmation,or consequence,is true;otherwise false.For true and false are attributes of speech,not of things.And where speech is not,there is neither truth nor falsehood.Error there may be,as when we expect that which shall not be,or suspect what has not been;but in neither case can a man be charged with untruth.
Seeing then that truth consisteth in the right ordering of names in our affirmations,a man that seeketh precise truth had need to remember what every name he uses stands for,and to place it accordingly;or else he will find himself entangled in words,as a bird in lime twigs;the more he struggles,the more belimed.And therefore in geometry (which is the only science that it hath pleased God hitherto to bestow on mankind),men begin at settling the significations of their words;which settling of significations,they call definitions,and place them in the beginning of their reckoning.
By this it appears how necessary it is for any man that aspires to true knowledge to examine the definitions of former authors;and either to correct them,where they are negligently set down,or to make them himself.For the errors of definitions multiply themselves,according as the reckoning proceeds,and lead men into absurdities,which at last they see,but cannot avoid,without reckoning anew from the beginning;in which lies the foundation of their errors.From whence it happens that they which trust to books do as they that cast up many little sums into a greater,without considering whether those little sums were rightly cast up or not;and at last finding the error visible,and not mistrusting their first grounds,know not which way to clear themselves,spend time in fluttering over their books;as birds that entering by the chimney,and finding themselves enclosed in a chamber,flutter at the false light of a glass window,for want of wit to consider which way they came in.So that in the right definition of names lies the first use of speech;which is the acquisition of science:and in wrong,or no definitions,lies the first abuse;from which proceed all false and senseless tenets;which make those men that take their instruction from the authority of books,and not from their own meditation,to be as much below the condition of ignorant men as men endued with true science are above it.For between true science and erroneous doctrines,ignorance is in the middle.Natural sense and imagination are not subject to absurdity.Nature itself cannot err:and as men abound in copiousness of language;so they become more wise,or more mad,than ordinary.Nor is it possible without letters for any man to become either excellently wise or (unless his memory be hurt by disease,or ill constitution of organs)excellently foolish.For words are wise men's counters;they do but reckon by them:but they are the money of fools,that value them by the authority of an Aristotle,a Cicero,or a Thomas,or any other doctor whatsoever,if but a man.