Suppose you have two glasses of water before you; one empty, the other half full. Now suppose we pour water out of the half-full glass into the empty one, and imagine that the half-full glass becomes fuller and fuller be cause of what we are doing. The materialist would consider this kind of thing foolish; but, my dear friends, with a concept suitable for meditation it is not a question of its reality but of whether it is one which will form ideas in the soul. Just because it relates to nothing real, it can direct our senses away from reality. It may be a symbol especially for that soul-process which we describe as the mystery of love. The process of love is something like that half-full glass from which man pours into the empty one, and which thereby becomes fuller and fuller. The soul does not become more empty, it becomes fuller in the same measure in which it gives; and in this way that symbol may have great significance.
Source: Rudolf Steiner – GA 150 – Macrocosm and Microcosm – Paris, May 5, 1913