In [whitehead’s] description of the relation of whole to part, there are, however, two assumptions which we have ignored in our theory of the action of the computing machine, and it is these assumptions which permit of analytic continuation, a going toward continuity. He supposes that there can exist an event which has no least part, and that if A is part of C, then there is always an event B, such that A is a part of Band B is a part of C. Apparently a computing machine, quantized as ours, is not built on either of these assumptions. We have supposed a least signal, that is to say, a signal which either occurs or does not occur. That least signal is a proposition “on the move.” It is true or else it is false, and it occurs at some particular time and at some particular place. Since the number of relays is finite, these can be ordered and a number assigned to each, and since we can quantize time in units equal to relay time, we can start counting at any particular instant and, by subscripting the number of a relay by a number representing the time of a signal there, we can construct statements in which the signal of a given relay is expressed in terms of those signals which reach it. Consider for a moment a computing machine in which there are no closed paths, that is, no circuits around which signals may chase their tails. In such a system each signal, implying its antecedents, implies a signal of a relay nearer to the receptors until we arrive ultimately at them.