The soul is not creative; it exercises no influence on nature; it is only perceptive, observant, cognising, only a witness of nature. Nature is illumined by the proximity of the soul, and the soul gives witness of nature; nature takes its light from the soul, just as a white crystal appears red in the proximity of a red substance.[377] The object of human life is to obtain liberation from the fetters of the body which bind the soul. The office of true knowledge is to set the soul free from the body, from nature. Man must grasp the difference of the soul and the body; he must understand that beside the body and nature, the soul is a completely self-existent being. The union of the soul and the body is nothing but deception, error, appearance. "In truth, the soul is neither bound nor free, nor a wanderer; nature alone is bound or free or migratory."[378] The soul seems to be bound to nature, but is not so. This appearance must be removed; the soul must recognise that it is not nature. When the soul has once penetrated nature it turns from it, and nature turns from the soul. The "unveiling of the spirit" from the case of nature is the liberation of the soul; by knowledge "release is brought about; by its opposite bondage."[379] By conceiving the absolute independence of the soul, man sets himself free from nature and his body; the idea of this independence is release. With this idea the man of knowledge surrenders his body; he is no longer affected or disturbed by it; even though his natural life continues, he looks on the body only "as on the movement of the wheel by virtue of the impulse once communicated to it."[380]