9. But it will be here said that, if _moral knowledge_ be placed in the contemplation of our own _moral ideas_, and those, as other modes, be of our own making, what strange notions will there be of _justice_ and _temperance_? What confusion of virtues and vices, if everyone may make what _ideas_ of them he pleases? No confusion or disorder in the things themselves, nor the reasonings about them; no more than (in mathematics) there would be a disturbance in the demonstration, or a change in the properties of figures and their relations one to another, if a man should make a triangle with four corners, or a _trapezium_ with four right angles: that is in plain _English_, change the names of the figures and call that by one name which mathematicians called ordinarily by another. For let a man make to himself the _idea_ of a figure with three angles whereof one is a right one, and call it, if he please, _equilaterum_ or _trapezium_ or anything else, the properties of and demonstrations about that _idea_ will be the same as if he called it a _rectangular-triangle_. I confess, the change of the name, by the impropriety of speech, will at first disturb him who knows not what _idea_ it stands for; but as soon as the figure is drawn, the consequences and demonstrations are plain and clear. Just the same is it in _moral knowledge_: let a man have the _idea_ of taking from others, without their consent, what their honest industry has possessed them of, and call this _justice_ if he please. He that takes the name here without the _idea_ put to it will be mistaken, by joining another _idea_ of his own to that name; but strip the _idea_ of that name or take it such as it is in the speaker's mind, and the same things will agree to it as if you called it _injustice_. Indeed, wrong names in moral discourses breed usually more disorder, because they are not so easily rectified as in mathematics, where the figure once drawn and seen makes the name useless and of no force. For what need of a sign, when the thing signified is present and in view? But in moral names, that cannot be so easily and shortly done, because of the many decompositions that go to the making up of the complex _ideas_ of those modes. But yet for all this, the _miscalling_ of any of those _ideas_, contrary to the usual signification of the words of that language, hinders not but that we may have certain and demonstrative knowledge of their several agreements and disagreements, if we will carefully, as in mathematics, keep to the same precise _ideas_ and trace them in their several relations one to another, without being led away by their names. If we but separate the _idea_ under consideration from the sign that stands for it, our knowledge goes equally on in the discovery of real truth and certainty, whatever sounds we make use of. ~ An Essay Concerning Human Understanding Chapter IV: Of the Reality of Knowledge