When someone does not know that the word ʿaqār refers to wine, he is told, “It is wine,” or given any of its other names, and thus he understands. If he has no acquaintance at all with the very substance of wine, he is instructed by way of something akin to it and told, “It is a beverage.” Once he has conceived the common element shared by beverages, the differentiating trait is added: “It is intoxicating.”
Yet explaining his conception of “intoxicating” raises the same issue as explaining his conception of “wine.” Should he be ignorant of what an intoxicant actually is, it can be defined for him only by recourse to something analogous. One says, “It is the loss of reason,” but that is a genus embracing sleep, madness, fainting, and drunkenness. Drunkenness must therefore be singled out: “the loss of reason accompanied by pleasure.” That pleasure, however, must already have been envisaged through experiences of eating, drinking, and the like.
This shows that the benefit of definitions may at times be weaker than that of names. A definition acquaints one with a thing through its analogue, whereas a name suffices for the person who already knows the thing itself.
In reality, a definition consists in describing the definiendum with qualities that separate it from everything else. Such qualities yield only reported knowledge of the object, and a report is not the same as direct sight; the one who has seen an object is not like the one who knows it merely through its features and embellishments. Hence, whoever knows the referent in its very reality finds the name alone sufficient, as noted earlier. Whoever does not know it firsthand will not gain from the definition what the name gives to the one who does, for in that latter case the name denotes the very entity already recognized. To the person unacquainted with the entity, the definition grants knowledge only of the class, not of the individual—much as someone who has never tasted wine imagines the pleasure of drinking it by analogy with the pleasure of bread and meat, even though the two pleasures are markedly different.
Our purpose is not to claim that the usefulness of definitions is always and absolutely weaker; rather, our point is that it belongs to the same order