According to his book, the world is twofold for man in accordance with his twofold attitude. 'I and Thou' and 'I and It'.
When a human being turns to another as another, as a particular and specific person to be addressed, and tries to communicate with him through language or silence, something takes place between them which is not found elsewhere in nature. Buber called this meeting between men the sphere of the between. All real living is meeting.
I can perceive it as movement:
I can dissipate it and perpetuate it in number...
In all this the tree remains my object, occupies space and time, and has its nature and constitution.
It can, however, also come about, if I have both will and grace, that in considering the tree I become bound up in relation to it. The tree is no longer It. I have been seized by the power of exclusiveness.
Conscious life means the return of cosmic being as human becoming. Spirit appears in time as a product, even as a by product of nature, yet it is in spirit that nature is timelessly enveloped.
The yearning is for the cosmic connection, with its true Thou, of this life that has burst forth into spirit.
For no 'thing' is a ready-made part of an experience : only in the strength, acting and being acted upon, of what is over against men, is anything made accessible.
I do not behold it as a thing among the "inner" things nor as an image of my "fancy," but as that which exists in the present. If test is made of its objectivity the form is certainly not "there". Yet what is actually so much present as it is. And the relation in which I stand to it is real, for it affects me, as I affect it.
Between you and it there is mutual giving: You cannot make yourself understood with others concerning it, you are alone with it. But it teaches you to meet others, and to hold your ground when you meet them. Through the graciousness of its comings and the solemn sadness of its goings it leads you away to the Thou in which the parallel lines of relations meet.
Another way, In so far as man rests satisfied with the things that he experiences and uses, he lives in the past, and his moment has no present content. He has nothing but objects. But objects subsist in time that has been.
The present is not fugitive and transient, but continually present and enduring. The object is not duration, but cessation, suspension, a breaking off and cutting clear and hardening, absence of relation and of present being. True beings are lived in the present, the life of objects is in the past.
The word I Thou is not helping you to sustain life, it is only helping you to glimpse eternity.
And all seriousness of truth hear this, without I and It Man can't live, but he who lives It alone he is not a man.
by Martin Buber you can read his book here.
and further reading here.