That would be a curious chapter of the history of thought, in which were demonstrated the errors that had been introduced and embedded in our minds by the use of certain words, which in the course of time gradually developed a meaning the exact opposite of that which they had at the first. For instance, matter is generally represented as something tangible, that is to say, all are agreed in finding it devoid of mind, and it is a sign of condemnation to say of a century it is materialistic. Yet we who daily touch tangible objects, such as stone, metal, wood, never succeed in putting our hands on matter as such; we should not know where to find it. Does this arise from the fact that matter is not tangible? The Latin word _materia_ had originally the meaning of the wood of a tree, then of wood or timber for building. This meaning was generalised so as to include solid bodies capable of taking various shapes. When idols were fashioned a distinction was made between the wood and the shape which emerged; and afterwards, when sculptors carved statues of marble or of metal, the marble and metal again received the name of matter or material; and when it was asked of what all tangible objects were made, even the world on which we live, the answer was that all were made of matter whilst they differ in form. In this way have we become possessed of our word matter, to which nothing tangible quite corresponds; and no doubt, owing to its complexity of meaning, it has not ceased to exercise the minds of learned men. If philosophers have not been able to explain accurately the meaning of matter, physicists have not been more successful, since what we call matter does not come under our senses. The word might have escaped this ill fate had it always been used only by philosophers “who try only to use words that have been clearly defined, but names are used by the wise and the foolish, and the foolish, as we know, are in such an immense majority that the wonder is that words have any definite sense left at all.”[132] Max Müller says: “I am quite willing to admit that matter may be called the objective cause of all that we perceive. For the very reason, however, that it is a cause, matter can never fall under the cognisance of our senses. All that we can predicate of matter is that it causes our sensations, that it exists in space and time, that it is one, but appears under an endless variety of phenomenal forms, that it remains unchanged in the change of outward appearances.”[133]