This means that in change such as this, change, that is, which has duration, repetition is out of the question. Take a song in which the last line is sung twice over as a refrain: the notes, we say, are repeated, but the second time the line occurs the actual effect produced is different, and that, indeed, is the whole point of a refrain. This illustrates the second important difference which Bergson wants to bring out between the forms of change which belong respectively to non-logical facts and to the logical abstractions by which we describe them, that is between duration as contrasted with a logical series of stages. The notes are abstractions assumed to explain the effect produced, which is the actual fact directly known. The notes are stages in a logical series of change, but their effects, the actual fact, changes as a process of duration. From this difference in their ways of changing there follows an important difference between fact and abstraction, namely that, while the notes can be repeated over again, the effect will never be the same as before. This is because the notes, being abstractions, are not affected by their relations which give them their position in the logical series which they form, while their effect, being a changing process, depends for its flavour upon its position in the whole duration to which it belongs: this flavour grows out of the whole of what has gone before, and since this whole is itself always growing by the addition of more and more “later stages,” the effect which it goes to produce can never be the same twice over. This is why Bergson calls duration “creative.” No “two” positions in a creative process of duration can have an identical past history, every “later” one will have more history, every “earlier” one less. In a logical series, on the other hand, there is no reason why the same term should not occur over and over again at different points in the course of the series, since in a logical series every term, being distinct from every other and only joined to it by external relations, is what it is independently of its position. If Bergson is right therefore in saying that abstractions change as a logical series while the actual facts change as a creative process of duration, it follows that, while our descriptions and explanations may contain repetitions the actual fact to which we intend these explanations to apply, cannot. This, if true, is a very important difference between facts and abstractions which common sense entirely overlooks when it assumes that we are directly acquainted with common qualities.