The concept, to which we have risen from intuition, does not live in empty space. It does not exist as a mere concept, or as something abstract. The air it breathes is the intuition itself, from which it detaches itself, but in whose ambient it continues. If these images seem unsuitable, or somewhat drawn from the sphere of representations, we may choose others, such as that, which we used on another occasion, of the second grade, which, to be second, must rest upon the first, and, in a certain sense, be the first. The concept does not exist, and cannot exist, save in the intuitive and expressive forms, or in what is called language. To think is also to speak; he who does not express, or does not know how to express his concept, does not possess it: at the most, he presumes or hopes to possess it. Not only is there never in reality an unexpressed representation, a pictorial vision unpainted, or a song unsung; but there is never even a concept which is simply thought and not also translated into words. We have previously defended this thesis against the objections which are wont to be made to it.[1] But in order to recapitulate and thus to avoid the misunderstandings which might arise from the abbreviating formulæ which we use, it will be well to repeat that the concept is not expressed only in the so-called vocal or verbal forms; and if we mention these more than others, it will be by synecdoche, that is to say, when we refer to them, we desire to take them as representative of all the others. Undoubtedly, the affirmation that the concept can also be expressed in non-verbal form may cause surprise. It will be said that geometry itself, in so far as it describes geometrical figures, at the same time employs or implies speech; and we shall be ironically challenged to attempt to set the _Critique of Pure Reason_ to music or to make a building of Newton's _Natural Philosophy._ But we must carefully beware of breaking up the unity of the intuitive spirit, because errors arise and become incorrigible, precisely through such breaking up. Words, tones, colours, and lines are physical abstractions, and only by abstraction can they be successfully separated. In reality, he who looks at a picture with his eyes also speaks it in words to himself; he who sings an air also has its words in his spirit; he who builds a palace or a church speaks, sings, and makes music; he who reads a poem sings, paints, sculptures, constructs. _The Critique of Pure Reason_ cannot be set to music, because it already has its music; the _Natural Philosophy_ cannot be built in stone, because it is already architectonic; in exactly the same way that the _Transfiguration_ cannot be turned into a symphony in four movements, or the _Promessi Sposi_ into a series of pictures. Thus the challenge, if made, would testify to the lack of reflection on the part of the challengers, for they would confuse physical distinctions with the real and concrete act of the intuitive spirit.