As the rust is natural to the iron and as the milk turns sour, so it is with the heart, when it becomes rusted and its feeling, which by nature is as pure as milk, turns sour. Then nothing in the world is tasteful to that person and life with all its beauty becomes worthless. It is this condition which must be avoided. An adept must keep his mind pure from rust.

The rust comes from allowing the heart to bear malice and spite against anyone, by having hatred and prejudice against anyone, by wanting to take revenge, by looking down upon another with contempt, and by the feeling of jealousy, rivalry or envy. The heart wants a constant care to keep it from getting rusted, for the nature of this life of illusion is such that some little unimportant things, which are not of the least value, coming from the outer life, the heart may be affected by, and the rust may be produced as the mere touch of water can produce rust upon the iron. Once the feeling has become soured it is difficult, if not impossible, to turn it sweet again as to make the sour milk sweet.

A soul has brought from Heaven its love for sweet. It may after coming on earth develop a taste for salt, sour, or bitter, but its innate longing is always for the sweet, and what its life needs most is not sugar, which is required in some degree for physical health, but the sweet which is the original property of his heart and which is needed most for his true happiness and real well-being.