An examination of the disputes which have always centered round this question of continuity renders it clear that they are almost invariably rooted in the ambiguity of the term. Analysis shows that it is used with two very different meanings. There is first of all what might be called the older, common-sense meaning; and then the modern, mathematical use of the term. The first may be best illustrated by considering the conception of a continuous material substance. Such a conception has appeared at various times and in various connections in physical science, as opposed to the atomic view of material substance. A continuous substance is structureless in the sense that it is not built up by the aggregation of a number of small elementary substances. Such a substance, though it seems paradoxical at first sight, would be indivisible; for the separation of an ordinary substance into two parts consists in overcoming the mutual forces between certain of its elementary particles. But in the case of our so-called 'continuous' substance, where there are no elementary particles, a moment's thought suffices to show that the operation of division could not actually be performed at all—all of which simply comes to this, that in such a case, when we say that our substance is continuous, we really mean that it is one—not relatively, but absolutely one and indivisible. In fact, the use of the word 'continuous' in this way is both arbitrary and unnecessary. Such continuity is just unity. Nothing more nor less than this is meant by the continuity of experience. The individual experience is an indivisible unity. The use of all such words as 'interpenetration' is simply the groping after the expression of that one fact—experience is one and indivisible. And, after all, what more do we need? There is no great difficulty in the conception of such a unity. It is one, because it is presented to one subject. The introduction of the additional notion of continuity is entirely gratuitous, and at once raises fresh and irrelevant difficulties. Much dispute and confusion would be avoided, if people would stop talking about the continuity of experience, and simply speak of its unity.
The modern tendency is rightly to restrict and make definite the use of the word 'continuity,' by employing it with one mean-
