【Symmetry】 , 【proportion】 ,  【balance】 ,  【harmony】  are comparable chiefly as used in the arts of design and decoration to mean a quality which gives aesthetic pleasure and which depends upon the proper relating of details and parts to each other (as in magnitude, or arrangement) and to the consequent effect produced by the whole.

【Symmetry】 implies a median line or an axis on either side of which the details correspond (as in size, form, and placing). Often it implies such mathematical precision especially in arrangement of elements or parts as is observable in the corresponding halves of a perfect crystal, in a geometrically regular star, or in the conventionalized leaf or flower of decorative design, but, in its stress of mechanical precision,  【symmetry】 may sometimes suggest an arid sterile quality, lacking in true artistic expression.

【Proportion】 implies a grace or beauty, independent of a thing’s actual magnitude, duration, or intensity, that stems from the measured fitness of every one of its details and the consequent perfection of the whole.

【Balance】  is sometimes employed as an equivalent of  【symmetry】  , but it can be used distinctively to imply equality of values rather than repetition of details or parts and a massing of different things (as light and shade, sharply contrasted colors, or figures and background) so that each one tends to offset the other or to reduce the other’s emphasis without loss of significance on either side.  【Balance】 implies as its aesthetic object an inducing of a pleasant satisfaction in the thing’s quiet beauty or of a delight in the unified yet varied effect of the whole.

【Harmony】  , when used specifically in reference to the arts of design and decoration, retains as its leading implication the same idea as is involved in its general sense (see  【HARMONY】 1 ), that of beauty resulting from a perfect interrelation of details and their fusion into an agreeable whole. However it often denotes specifically the aesthetic impression produced by something which manifests 【symmetry】 , 【proportion】 , or 【balance】 , or these qualities in combination.