Martin Buber (1878-1965) was born in Vienna, and he studies philosophy and art at the Universities of Vienna, Berlin, and Zurich. In his twenties, he was an active Zionist. He stimulated a revival of Hasidism, a mystical movement that swept East European Jewry in the eighteenth and nineteenth centuries. He taught social philosophy from 1938-51 at Hebrew University in Jerusalem. His most popular book in the United States is I and Thou, trans. Walter Kaufmann (NY: Charles Scribner's Sons, [1923] 1970). Here is a summary of some key ideas from the beginning of that book.
There are two ways of relating (properly speaking, to "stand in relation" pertains only to the first mode): (1) with your whole being--meeting the whole being of the other: an "I-You" [or Thou] relationship or (2) with part of yourself, focusing on to a selected aspect of the other: an "I-It" connection. Relation takes place not as an inner experience but between the I and the You. In the I-It mode, the object is located in an objective space and time, amid other objects. In the I-You mode, the other "fills the firmament," "has no borders"; "everything else lives in [the other's] light." In the I-You mode, the person is being fully with the other.
The world of relation arises in life with
Nature (e.g., the tree [pp. 57-58, Kaufman translation], which I can perceive with excellent aesthetic sensitivity, biotic intuition, or the heights of scientific understanding, but not until "will and grace are joined" am I drawn into relation. This is not a religious or mystical experience, and none of the aesthetic, vital, or scientific awareness needs to be suppressed.)
Human beings (p. 59)
Spiritual beings, e.g., God. "Extended, the lines of relationships intersect in the eternal You. Every single You is a glimpse of that. Through every single You the basic word addresses the eternal You" (p. 123).