Ideas cannot be classed as true and false. The idea is necessarily true. An idea that can be disputed is an idea mingled with concrete notions, that is to say, a truth. The work of disassociation tends, precisely, to free the truth from all its fragile part, in order to obtain the pure, one, and consequently unassailable idea. But if words were never used save in their unique and absolute sense, connected discourse would be difficult. There must be left a little of that vagueness and flexibility which usage has given them; and, in particular, too much stress must not be laid upon the gap separating the abstract from the concrete. There is an intermediate state between ice and water--that in which the latter begins to congeal, when it still cracks and yields under the pressure of the hand plunged into it. Perhaps we should not even demand that the words contained in philosophic handbooks should abdicate all pretension to ambiguity. The idea of army, which aroused serious polemics, and which was liberated an instant, only to be obscured anew, is one of those that border on the concrete and cannot be spoken of without minute references to reality. The idea of justice, on the contrary, can be considered in itself, _in abstracto_. In the inquiry made by M. Ribot on the subject of general ideas, almost all those who heard the word Justice pronounced, saw, in their mind's eye, the legendary lady with the scales. There is, in this traditional representation of an abstract idea, a notion of the very origin of that idea.