Some matters therefore there are, which the soul or mind apprehends through itself--others, which it perceives through the bodily organs. To the latter class belong the sensible qualities, hardness, softness, heat, sweetness, &c., which it perceives through the bodily organs; and which animals, as well as men, are by nature competent to perceive immediately at birth. To the former class belong existence (substance, essence), sameness, difference, likeness, unlikeness, honourable, base, good, evil, &c., which the mind apprehends through itself alone. But the mind is not competent to apprehend this latter class, as it perceives the former, immediately at birth. Nor does such competence belong to all men and animals; but only to a select fraction of men, who acquire it with difficulty and after a long time through laborious education. The mind arrives at these purely mental apprehensions, only by going over, and comparing with each other, the simple impressions of sense; by looking at their relations with each other; and by computing the future from the present and past.[96] Such comparisons and computations are a difficult and gradual attainment; accomplished only by a few, and out of the reach of most men. But without them, no one can apprehend real existence (essence, or substance), or arrive at truth: and without truth, there can be no knowledge. [Footnote 96: Plato, Theætêt. p. 186 B. [Greek: Tê\n de/ ge ou)si/an kai\ o(/ ti e)/ston kai\ tê\n e)nantio/têta pro\s a)llê/lô] (of hardness and softness) [Greek: kai\ tê\n ou)si/an au)= tê=s e)nantio/têtos, au)tê\ ê( psuchê\ _e)paniou=sa kai\ xumba/llousa pro\s a)/llêla kri/nein peira=tai ê(mi=n_ . . . Ou)kou=n ta\ me\n eu)thu\s genome/nois pa/resti phu/sei ai)stha/nesthai a)nthrô/pois te kai\ thêri/ois, o(/sa dia\ tou= sô/matos pathê/mata e)pi\ tê\n psuchê\n tei/nei; _ ta\ de\ peri\ tou/tôn a)nalogi/smata_, pro/s te ou)si/an kai\ ô)phelei/an _mo/gis_ kai\ e)n pollô=| chro/nô| dia\ pollô=n _pragma/tôn kai\ paidei/as paragi/gnetai, oi(=s a)\n kai\ paragi/gnêtai.]] [Side-note: Sokrates maintains that knowledge is to be found, not in the Sensible Perceptions themselves, but in the comparisons add computations of the mind respecting them.] The result therefore is (concludes Sokrates), _That knowledge is not sensible perception_: that it is not to be found in the perceptions of sense themselves, which do not apprehend real essence, and therefore not truth--but in the comparisons and computations respecting them, and in the relations between them, made and apprehended by the mind itself.[97] Plato declares good and evil, honourable and base, &c., to be among matters most especially relative, perceived by the mind computing past and present in reference to future.[98]