The ablest detailed account of the relativity of spatial position readily accessible to the English reader, will be found in Mr. Russell’s _Foundations of Geometry_, chaps. iiiA, iv. Mr. Russell has since, in _Mind_ for July 1901, attempted to prove the opposite view, that positions in space and time are _inherently_ distinct, but without discussing his own previous arguments for relativity. Into the purely mathematical part of Mr. Russell’s later contentions I am not competent to enter. I may, however, suggest that the question of Metaphysics cannot be decided merely by urging, as Mr. Russell does, that fewer assumptions are required to construct a geometry on the hypothesis of absolute than on that of relative position. The superior convenience of an assumption for certain special purposes is no proof of its ultimate intelligibility. And when Mr. Russell goes on to admit that points in space are _indistinguishable for us_, he seems to me to give up his case. For is not this to admit that, after all, the space with which we deal in our geometrical science is relative from beginning to end? How differences of quality of which we, by hypothesis, can know nothing, can help or hinder our scientific constructions, it is indeed hard to see. Footnote 149: This may be brought home even to those who, like myself, are not mathematicians, by the perusal of such a work as Lobatchevsky’s _Untersuchungen zur Theorie der Parallel-Linien_, where a consistent geometry of triangles is constructed in entire independence of the postulate of parallelism. Of course, in the end it must be a mere question of nomenclature whether a form of serial order independent of these quasi-empirical restrictions is to be called “space” or not. Footnote 150: It must be carefully remembered that the essential defect of the indefinite regress is not its interminableness, but its monotony. We ourselves held that Reality is an individual composed of lesser individuals which _repeat_ the structure of the whole, and that the number of these individuals need not be finite. But, in our view, the higher the order of individuality the more self-explanatory was its structure, whereas in the indefinite regress an incomprehensible construction is endlessly repeated _in the same form_. Footnote 151: Normally, that is; for brevity’s sake I omit to note the possible case of a coherent dream-life continued from night to night. In principle there would be a difference between the case of the space and time of _such_ a dream-life and those of our waking hours. Footnote 152: