Man by his nature is located in a process of comprehending and understanding the world, of being interested in the world—if we consider “interest” in its original etymological sense of inter-esse, of being-within—a process by which the division between a rigid subject and an equally rigid, externally located object is overcome in favor of the idea of a constant relationship in which (as the Buddhists say) “I do not only see the rose, the rose also sees me.” This is just a special formulation of this procedural, reciprocal relationship of man to the world.
There is more: this being-in-the-world, this giving-oneself-to-the-world, this self-transformation in the act of life, is only possible when man loses his greediness and stinginess and abandons his self as an isolated, fixed ego that stands opposed to the world.
Only when man abandons this self, when he can empty himself (to use the language of mystics), only then can he fill himself entirely. For he must be empty of his egotistical self in order to become full of what comes to him from the world. It does not matter whether that something is a person or nature or an idea. The person who is filled up with himself is neither open nor free to give himself.
– Erich Fromm, The Essential Fromm : Life Between Having and Being