The case of RYTHM is more complex. For, although we usually think of Rythm as a relation of _two_ items, it is in reality a relation of four (or more ); because what we remember and expect is a mixture of similarity with dissimilarity between lengths, directions or impacts. OR IMPACTS. For with Rythm we come to another point illustrative of the fact that all shape-elements depend upon our own activity and its modes. A rythmical arrangement is not necessarily one between _objectively_ alternated elements like objectively longer or shorter lines of a pattern, or _objectively_ higher or lower or longer and shorter notes. Rythm exists equally where the objective data, the sense stimulations, are uniform, as is the case with the ticks of a clock. These ticks would be registered as exactly similar by appropriate instruments. But our mind is not such an impassive instrument: our mind (whatever our mind may really be) is subject to an alternation of _more_ and _less,_ of _vivid_ and _less vivid, important_ and _less important,_ of _strong_ and _weak;_ and the objectively similar stimulations from outside, of sound or colour or light, are perceived as vivid or less vivid, important or less important, according to the beat of this mutual alternation with which they coincide: thus the uniform, ticking of the clock will be perceived by us as a succession in which the stress, that is the importance, is thrown upon the first or the second member of a group; and the recollection and expectation are therefore of a unity of dissimilar importance. We hear STRONG-WEAK; and remembering _strong-weak,_ we make a new _strong-weak_ out of that objective uniformity. Here there is no objective reason for one rythm more than another; and we express this by saying that the tickings of a clock have no intrinsic form. For _Form,_ or as I prefer to call it, _Shape,_ although it exists only in the mind capable of establishing and correlating its constituent relationships, takes an objective existence when the material stimulations from the outer world are such as to force all normally constituted minds to the same series and combinations of perceptive acts; a fact which explains why the artist can transmit the shapes existing in his own mind to the mind of a beholder or hearer by combining certain objective stimulations, say those of pigments on paper or of sound vibrations in time, so as to provoke perceptive activities similar to those which would, _ceteris paribus,_ have been provoked in himself if that shape had not existed first of all _only_ in his mind.