Where there is a hole this hole has a tendency to become larger, and where there is a little substance there is a tendency for that substance to increase; this shows the tendencies of spirit and matter, the continual conflict that exists between spirit and matter. On the part of matter there is always a tendency to absorb, and on the part of spirit there is always a tendency to assimilate. Mortality, therefore, belongs to substance, not to spirit; immortality belongs to the spirit.