Yet, Buber, felt that the I-It relationship had achieved a type of dominance that overshadowed the importance of I-Thou:
In our age the I-It relation, gigantically swollen, has usurped, practically uncontested, the mastery and the rule. The I of this relation, an I that possesses all, makes all, succeeds with all, this I that is unable to say Thou . . . can naturally acknowledge neither God nor any genuine absolute which manifests itself to men as of non-human origin. It steps in between and shuts off from us the light of heaven.
In contrast to I-It, I-Thou describes a relationship that is reciprocal, mutual, and experiential. It is in the meeting between I and Thou that a person experiences her or his whole being and the being of the other. This is not an individual process, but a process of relation, the dialogue between one and another. In this relationship, one does not define or contain the other, but rather is affected by the other. No concepts or analyses are needed; the relation is simply experienced as each influences the other.
This relation can be understood as partially mystical, yet Buber wanted this relation to be about the present, not a mystical union separate from the physical world. The contrast between I-It and I-Thou reflects the difference between the mechanistic and objective world of science and the aesthetic, artistic, and religious world of Thou. Buber did not intend to remove the I-It relation, but argued that modern society has emphasized it too much at the expense of the creative impulse of the artist and the religious experience of the aesthetic. The I-It relation is not emotionally involved in what it describes, and it is not open to the change that it may encounter when confronted with Thou. It is content to define and remain distant, uninterested in the world around it.
Thou may be another person, nature, or the eternal Thou, God. In speaking of relating to nature, a tree may be classified and understood as an object or it may be experienced as Thou. The I-Thou relation focuses on how the experience of the tree affects and changes a person, rather than the tree simply becoming an object that is identified. Buber did not advocate for any type of dualism, but understood nature and God as part of the kingdom of God.
There is not one realm of the spirit and another of nature; there is only the growing kingdom of God. God is not spirit, but what we call spirit and what we call nature hail equally from the God who is beyond and equally unconditioned by both, and whose kingdom reaches its fullness in the complete unity of spirit and nature. (1966: 28)
The importance of the I-Thou relation for spiritual development highlights the importance of relational engagement with the divine. This should not be seen as a mystical union that shuns nature, but rather an active engagement with God and his creation. Relating to God through the I-It relation transforms God into an object that is simply defined and abstracted but never experienced. When God is the eternal Thou, the person is able to open his or her self to being impacted by the divine, and the person is able to impact God. The relationship is mutual and reciprocal, focusing on how people allow their life and their person to be persuaded and moved in connection to the divine. This is not a relationship that occurs through having correct concepts or beliefs, but through openness and humility that allow two subjects to mutually interact with one another.