_Sokr._--According to your explanation, then, it is only the temperate man who knows himself. He alone is able to examine himself, and thus to find out what he really knows and does not know: he alone is able to examine others, and thus to find out what each man knows, or what each man only believes himself to know without really knowing. Temperance, or self-knowledge, is the knowledge what a man knows, and what he does not know.[15] Now two questions arise upon this: First, is it possible for a man to know, that he knows what he does know, and that he does not know what he does not know? Next, granting it to be possible, in what way do we gain by it? The first of these two questions involves much difficulty. How can there be any cognition, which is not cognition of a given _cognitum_, but cognition merely of other cognitions and non-cognitions? There is no vision except of some colour, no audition except of some sound: there can be no vision of visions, or audition of auditions. So likewise, all desire is desire of some pleasure; there is no desire of desires. All volition is volition of some good; there is no volition of volitions: all love applies to something beautiful--there is no love of other loves. The like is true of fear, opinion, &c. It would be singular therefore, if contrary to all these analogies, there were any cognition not of some _cognitum_, but of itself and other cognitions.[16] [Footnote 15: Plato, Charm. 167 A.] [Footnote 16: Plato, Charm. 167-168.] [Side-note: All knowledge must be relative to some object.] It is of the essence of cognition to be cognition of something, and to have its characteristic property with reference to some correlate.[17] What is greater, has its property of being greater in relation to something else, which is less--not in relation to itself. It cannot be greater than itself, for then it would also be less than itself. It cannot include in itself the characteristic property of the _correlatum_ as well as that of the _relatum_. So too about what is older, younger, heavier, lighter: there is always a something distinct, to which reference is made. Vision does not include in itself both the property of seeing, and that of being seen: the _videns_ is distinct from the _visum_. A movement implies something else to be moved: a heater something else to be heated. [Footnote 17: Plato, Charm. 168 B. [Greek: e)/sti me\n au(tê\ ê( e)pistê/mê tino\s e)pistê/mê, kai\ e)/chei tina toiau/tên du/namin ô(/ste tino\s ei)=nai.]] [Side-note: All properties are relative--every thing in nature has its characteristic property with reference to something else.]