66 A. F. RAVENSHEAR : perception of uniformity is the result of a selection and emphasis of certain features, commonly not noticed in our early acquaintance with the matter, which are brought to light by a comparison of those experiences with others. This emphasising of certain features and neglect of others the process of analysis or abstraction is not only a laying of stress on something in an isolated experience, but is also a selection and emphasising of other experiences. The bal- loon an apparent irregularity to the rule that heavy bodies fall when free is seen to exhibit uniformity when experience of hydrogen is brought into view ; and the different be- haviour of our friend under similar external circumstances shows uniformity when experience of varying bodily con- dition is brought into line with it. But these other ex- periences that must be employed to force the given ex- perience to yield up its uniformity may not be within the reach of any one individual. The uniformities shown in the return of certain of the comets are visible only to those who know how to rely upon records many hundred years old. The uniformities brought to light by statistics are nothing to him who cannot depend on an army of co- ^vorkers. If the individual indeed were to confine himself strictly to his own experience, Nature, far from seeming universally uniform, would seem infinitely capricious. The universal uniformity of Nature can be seen only by an analytical use of the experience of others as well as our own. Mere addition of obvious uniformities derived from other persons' experience might perhaps give a restricted field of uniform action ; but only by an intussusception of each other's experience does the universal extent of that field become known. But in laying stress on some features we ignore others. What of those we neglect ? the errors of observation, the individual variations when we are dealing with averages or elimination of chance, the ' irrelevant ' circumstances which make up the difference between the abstract concep- tion and the concrete experience. Is nature uniform only as far as the limits of errors of observation ? This question scarcely needs an answer ; but it furnishes an illustration of the preceding remarks on the use of the experience of others in the proof of Nature's uniformity. These neglected things are never intended to be neglected for ever. The ideally complete theory would take account of them all. Wherever at present this cannot be done the reason is that the appropriate experiences by which their apparent irregu- larity and caprice could be converted into law either have
