I contemplate a tree. 

I can accept it as a picture: a rigid pillar in a flood of light, or splashes of green traversed by the gentleness of the blue silver ground.

I can feel it as movement: the flowing veins around the sturdy, striving core, the sucking of the roots, the breathing of the leaves, the infinite commerce with earth and air--and the growing itself in its darkness.

I can assign it to a species and observe it as an instance, with an eye to its construction and its way of life.

I can overcome its uniqueness and form so rigorously that I recognize it only as an expression of the law--those laws according to which a constant opposition of forces is continually adjusted, or those laws according to which the elements mix and separate.

I can dissolve it into a number, into a pure relation between numbers, and eternalize it.

Throughout all of this the tree remains my object and has its place and its time span, its kind and condition.

But it can also happen, if will and grace are joined, that as I contemplate the tree I am drawn into a relation, and the tree ceases to be an It. The power of exclusiveness has seized me.

This does not require me to forego any of the modes of contemplation. There is nothing that I must not see in order to see, and there is no knowledge that I must forget. Rather is everything, picture and movement, species and instance, law and number included and inseparably fused.

Whatever belongs to the tree is included: its form and its mechanics, its colors and its chemistry, its conversation with the elements and its conversation with the stars--all this in its entirety.

The tree is no impression, no play of my imagination, no aspect of a mood; it confronts me bodily and has to deal with me as I must deal with it--only differently.

One should not try to dilute the meaning of the relation: relation is reciprocity.

Does the tree then have consciousness, similar to our own? I have no experience of that. But thinking that you have brought this off in your own case, must you again divide the indivisible? What I encounter is neither the soul of a tree nor a dryad, but the tree itself.

-Martin Buber, I and Thou

Source: http://www.myjewishlearning.com/holidays/Jewish_Holidays/Tu_Bishvat/Ideas_and_Beliefs/Rabbinic/Every_Person_is_a_Tree/I_and_Thou_a_Tree.shtml