Co-ordinate Species, when positive, have the least contrariety; but there are also opposites, namely, negatives, contradictories and fuller contraries. These may be regarded as either co-ordinate genera or the species of co-ordinate genera. Thus, _repose_ being a genus, _not-repose_ is by dichotomy a co-ordinate genus and is a negative and contradictory; then _activity_ (implying an end in view), _motion_ (limited to matter), _disturbance_ (implying changes from a state of calm), _tumult_, etc., are co-ordinate species of _not-repose_, and are therefore co-ordinate opposites, or contraries, of the species of _repose_. As for correlative words, like _master and slave_, _husband and wife_, etc., it may seem far-fetched to compare them with the sexes of the same species of plants or animals; but there is this resemblance between the two cases, that sexual names are correlative, as 'lioness,' and that one sex of a species, like a correlative name, cannot be defined without implying the other; for if a distinctive attribute of one sex be mentioned (as the lion's mane), it is implied that the other wants it, and apart from this implication the species is not defined: just as the definition of 'master' implies a 'slave' to obey. Common words, less precise than the terms of a scientific nomenclature, differ from them also in this, that the same word may occur in different genera. Thus, _sleep_ is a species of _repose_ as above; but it is also a species of _unconsciousness_, with co-ordinate species _swoon_, _hypnotic state_, etc. In fact, every word stands under as many distinct genera, at least, as there are simple or indefinable qualities to be enumerated in its definition. § 3. Partially similar to a scientific nomenclature, ordinary language has likewise a terminology for describing things according to their qualities and structure. Such is the function of all the names of colours, sounds, tastes, contrasts of temperature, of hardness, of pleasantness; in short, of all descriptive adjectives, and all names for the parts and processes of things. Any word connoting a quality may be used to describe many very different things, as long as they agree in that quality.