after them know the realities of things without their convention. If they themselves reflect, they will find that they know the realities of things without this conventional art. Yet they claimed that this art makes the realities of things known, and that these realities cannot be known except through it. Both claims are mistaken.

When they sought to achieve this, they had to distinguish between certain attributes and others. Since they made conception depend on what they deemed essential, they necessarily had to distinguish between what they regarded as essential and what they did not. This led them to distinguish between things that are alike, treating one attribute as essential but not another, although the two were equal or closely similar. Finding a distinction between things that are alike is impossible, and between closely similar things is difficult. What they seek is therefore either impossible or difficult to attain. If it is impossible, their undertaking fails altogether. If it is difficult, then even once attained, it adds nothing to what was already known before attaining it.

Thus, either they cannot meet the condition they have stipulated, or they meet it without achieving their intended aim. In either case, the definition they have devised is not a means of producing a conception of realities in the mind of someone who cannot conceive of them without a definition, although it may serve to distinguish what is defined in the same way that names do.

Fakhr al-Rāzī recognized the position held by the leading scholars of theology and established in his al-Muhassal (Compendium) and elsewhere that conceptions cannot be acquired. This is precisely what we mean when we say that a definition does not yield a conception of what is defined. This is “a point of great importance” that ought to be understood, for neglect of it has allowed corruption to enter