We shall not explain here all the forms of indirect derivation, or enumerate the forty-seven affixes used for this purpose. We shall quote only a few of them for the sake of example, in order to show the application of the principles enunciated above. If there is one suffix which is particularly useful to philosophers, it is that which enables one to derive from an adjective the name of the corresponding abstract quality; that is the Greek suffix _-otet_ and the Latin suffix _-itat_ (_-itud_), whence have come the French _-ité_, the English _-ity_, the Italian _-ita_, the Spanish _-itad_; and the German suffix _-heit_ or _-keit_, etc. We perceive here a logical relation well known and made use of in all our languages. It must find a place in the international language, but by what suffix ought it to be represented? Now, if one analyses the idea involved in this suffix, one will find that _beauty_, _health_, _blindness_, are simply the states or facts of being beautiful, healthy, blind. The idea involved in this suffix is then the idea of _being_, not the idea of existence, but the idea _of being_ such and such, the idea of attribution which is expressed by the copula _est_. It is natural, therefore, to represent it by the Indo-European stem of the verb _to be_, namely, _es_; _bel-es-o_ = _beauty_; _san-es-o_ = _health_; _blind-es-o_ = _blindness_. The fact that this suffix recalls a French suffix (_richesse_), an Italian suffix (_bellezza_), and an English suffix _-ness_ (_happiness_) employed in the same sense can only serve as an accessory confirmation of the above choice, which was dictated by logical motives. Moreover, this agrees perfectly with our general rules; _to be well_ will be translated by _esar sana_ or _san-esar_, and the fact of being well will be _saneso_ = _health_. Conversely, if we start from _saneso_ = _health_, we can form the verb _sanesar_ = _to be in (good) health_. Whatever may be the point of departure, there is no fear of making a mistake or "going off the rails" in forming these derivatives, if we observe the principle of reversibility. It would, therefore, be not only arbitrary, but absurd, to express _health_ by _sano_, which latter can only mean a healthy being. For one must not imagine, as is often stated, that an adjective expresses a quality; it expresses precisely _he who, or that which, possesses the quality in question_. That is why all our languages employ a suffix for the purpose of deriving from an adjective the name of the corresponding quality.