Even the stoics taught that spiritual purity leads to the harmony of man's entire being. Our physiological activity Is a function of the food we eat. The more we eat foods which are located higher up on the ladder of organic and animal world, the more active we become In the physical sense. Vladimir Soloviov.gives the following gradation of physical activity. Physical activity Is the least pronounced in the plant world.
Fish are more highly developed than plants, and birds are more highly developed than fish.
That Is why the physical energy derived from birds Is proportionately stronger than that derived from either fish or plants. Apart from its physiological aspect, fasting Is Important for spiritual development and the training of will. The Lord gave man the freedom of will so that he may do good deeds, seek the Truth and create beautiful things. But the freedom of will does not mean the absence of will , lack of volition, weakness of will or apathy. If man is given his freedom of will , than he must know what he wants, towards what end his will should be directed.