Scientific thinking, if guided by knowledge of the existence of etheric forces and their action, has no need of such an interpretation of the numerical relationships revealed in the physical world; for it knows them to be nothing but the last expression of the action of the chemical ether (hence occasionally also called ‘number-ether’ by Rudolf Steiner). To do justice to the appearance of measurable numerical relationships in nature, in whatever sphere, it is necessary to free ourselves from the abstract conception of number which governs modern scientific thought and to replace it by a more concrete one. We shall rind that for the existence of a certain number there may be two quite different reasons, although the method of establishing the number itself is the same in each case. A simple example will illustrate this.