Similarly with other cases of apparently rigid uniformity. As any one who has worked in a laboratory knows,[134] such results are in actual practice obtained by taking the mean of a long series of particular results and treating the minor divergences from this mean as non-existent because they are negligible for all practical purposes. In other words, the apparently rigid conformity of natural processes to uniform law is an inevitable consequence of the fact that we are debarred by various limitations of a subjective kind from following the course of any process in its individual detail, and have therefore to make all our inferences from the observation and comparison of series of processes sufficiently extended for individual differences to neutralise each other. But in all this there is absolutely no warrant for the conclusion that the course of any one individual process is absolutely uniform with that of any other. There is room within the uniformity got by these methods of comparison for an infinite variety of individual detail, of which our scientific constructions take no account, either because our means of observation are insufficient to detect it, or because, when detected, it is of no significance for the original object of our science—practical success in interference with the course of events. It is easy to point out some of the conditions upon which failure to detect actually existing individual deviations from uniformity may depend. Professor Royce has, in this connection, laid special stress upon one such condition, the limitation of what he calls the time-span of our attention. We are unable, as the student of Psychology knows, to attend to a process as a whole if its duration exceeds or falls short of certain narrow limits. Now, there seems no foundation in the nature of the attentive process for the special temporal limitations to which it is subject in our own experience, and we have no means of denying the possibility that there may be intelligent beings whose attention-span is much wider, or again, much more contracted, than our own. One can even conceive the possibility of a being with a power of varying the span of attention at will. Now, it is clear that if we could so vary our attention-span as to be able to take in as single wholes processes which are at present too rapid or too slow to be perceived by us in their individual detail, such a purely subjective change in the conditions of our own attention might reveal individuality and purpose where at present we see nothing but routine uniformity. In the same way, we can readily understand that a being with a much wider attention-span than our own might fail to see anything but purposeless routine in the course of human history. Supposing that we are placed in the midst of a universe of intelligent purposive action, it is clear that we can only hope to recognise the nature of that action in the case of beings who live, so to say, at the same rate as ourselves.