Martib Buber is well known as one of the founders of "Dialogical Philosophy" or "Philosophy of Dialouge The roots of Buber's "dialogical philosophy" are in German Romantic philosophy on the one hand, and on the other hand Buber's unmediated impression of Hassidic thought as he experienced it in his grandfather's house, from the well-known Shlomo Buber seminary. Most of his thought was published in his book "I and thou" in German in 1923.
Buber's thought is based on the assumption that "man is made I come with thou." Meaning: A person has no real "I" except when he can say "you" (or "thou") with all his might. Saying "thou" is the complete escape from my "I" into the absorption of the "thou" in its being, in its sincerity, and especially in telling me something of a quality that cannot be quantified (from the word "quantity") or explained to another person. Nor does it mean "thou" as a human being only.
The pinnacle of "dialogue" according to Buber is in the ability to meet through any true affinity with the "thou" the "thou are eternal". The third part of "I and thou" opens with the sentence "The elongated lines of affiliations meet with each other in the eternal self." That is, a person accustomed to meeting others in the "I am thou" will learn that in fact the "eternal you" - God - speaks to him through every concrete "thou" with whom he has created an affinity. Life is full of "signs" from the "eternal thou" that speaks to thou constantly. The person only has to tilt the ear. Buber's novelty is that no man can come to God but only through men (in this he is conducting a controversy with the Danish thinker Soren Kierkegaard).