The balance is a harmonious one. You will perhaps realise better what this means if you think for a moment of a balance that is not harmonious; for instance of a pair of hanging scales, in one pan of which there is a flat round one pound weight, exactly balancing a pound of candy in the other pan. We should not call this a harmonious balance. If we examine why it is not, it will help us to understand the meaning of harmony in composition. The reason is that there is no relation between the box of candy and the one pound weight, except that each weighs the same. On the other hand, in the picture every detail has some relation to the other details, and all are related to the whole. The whole, in fact, is a woven mass of contrasts and repetitions, in exact relation; very much as a composition of music is made up of exactly related contrasts and repetitions of sound notes. Alter one of these and there will be a discord, unless some other notes are altered to restore the harmony. Similarly if the artist had altered the shape of one of the details in his picture, or its color, or its lightness or darkness, there would have been a discord in the effect of his picture; it would no longer present the appearance of perfect oneness. He would have to alter some other parts to restore the harmony.