The relation of this universe to the world of fact is not unlike the relation between a tapestry picture and the scene which it imitates. You, practical man, are obliged to weave your image of the outer world upon the hard warp of your own mentality; which perpetually imposes its own convention, and checks the free representation of life. As a tapestry picture, however various and full of meaning, is ultimately reducible to little squares; so the world of common sense is ultimately reducible to a series of static elements conditioned by the machinery of the brain. Subtle curves, swift movement, delicate gradation, that machinery cannot represent. It leaves them out. From the countless suggestions, the tangle of many-coloured wools which the real world presents to you, you snatch one here and there. Of these you weave together those which are the most useful, the most obvious, the most often repeated: which make a tidy and coherent pattern when seen on the right side. Shut up with this symbolic picture, you soon drop into the habit of behaving to it as though it were not a representation but a thing. On it you fix your attention; with it you "unite." Yet, did you look at the wrong side, at the many short ends, the clumsy joins and patches, this simple philosophy might be disturbed. You would be forced to acknowledge the conventional character of the picture you have made so cleverly, the wholesale waste of material involved in the weaving of it: for only a few amongst the wealth of impressions we receive are seized and incorporated into our picture of the world. Further, it might occur to you that a slight alteration in the rhythm of the senses would place at your disposal a complete new range of material; opening your eyes and ears to sounds, colours, and movements now inaudible and invisible, removing from your universe those which you now regard as part of the established order of things. Even the strands which you have made use of might have been combined in some other way; with disastrous results to the "world of common sense," yet without any diminution of their own reality.