le
relations of lines and of sounds require to be ascertained
successively, the combination of those various single relations, their
relations with one another _as whole and parts,_ require to be
grasped by an intellectual synthesis; as much in the case of notes as
in the case of lines. If, in either case, we did not remember the first
measurement when we obtained the second, there would be no
perception of shape however elementary; which is the same as
saying that for an utterly oblivious mind there could be no
relationships, and therefore no meaning. In the case of Symmetry
the relations are not merely the lengths and directions of the single
lines, that is to say their relations to ourselves, and the relation
established by comparison between these single lines; there is now
also the relation of both to a third, itself of course related to
ourselves, indeed, as regards visible shape, usually answering to our
own axis. The expectation which is liable to fulfilling or balking is
therefore that of a repetition of this double relationship remembered
between the lengths and directions on one side, by the lengths and
directions on the other; and the repetition of a common relation to a
central item.

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 mut