Man is directly a natural being. As a natural being and as a living natural being he is on the one hand endowed with natural powers, vital powers — he is an active natural being. These forces exist in him as tendencies and abilities — as instincts. On the other hand, as a natural, corporeal, sensuous objective being he is a suffering, conditioned and limited creature, like animals and plants. ... A being which does not have its nature outside itself is not a natural being, and plays no part in the system of nature. A being which has no object outside itself is not an objective being.