Ich und Du, usually translated as I and Thou, is a book by Martin Buber, published in 1923.

It is Buber’s best-known work, setting forth his critique of modern objectification in relationships with others.

Buber's main proposition is that we may address existence in two ways: One of the major themes of the book is that human life finds its meaningfulness in relationships.

The essential character of "I–Thou" is the abandonment of the world of sensation, the melting of the between, so that the relationship with another "I" is foremost.

I–Thou is not a means to some object or goal, but a definitive relationship involving the whole being of each subject.

God is ever-present in human consciousness, manifesting in music, literature, and other forms of culture.

Martin Buber's work of I and Thou has had a profound and lasting impact on modern thinking, as well as the field of psychology in particular.

Figures in American history have been influenced by this work, including one of the founding fathers of modern humanistic psychology, Carl Rogers.

Rogers compares his person-centered therapy and the necessary psychological contact to the I–Thou relationship; while Buber does not completely agree, pointing out that the therapist-client relationship is on somewhat unequal footing, they do concede that there are momentary, true connections made between therapist and client that are "reciprocal" and have a degree of "mutuality".

[3] Buber's work also influenced the Civil Rights leader Martin Luther King Jr.

The "I–Thou" relationship is quoted in his Letter from Birmingham Jail and his sermon, "A Testament of Hope."

[5] The book has been translated to English twice, by Ronald Gregor Smith in 1937 and by Walter Kaufmann[6] in 1970.