Causality has an unlimited reign in the world of It. Every “physical” event that can be perceived by the senses, but also every “psychical” event existing or discovered in self-experience is necessarily valid as being caused and as causing. Further, events to which a teleological character may be attributed are as parts of the unbroken world of It not excepted from this causality; the continuum to which they belong certainly tolerates a teleology, but only as the reverse side worked into a part of causality, and not impairing its continuity and completeness.
The unlimited reign of causality in the world of It, of fundamental importance for the scientific ordering of nature, does not weigh heavily on man, who is not limited to the world of It, but can continually leave it for the world of relation. Here I and Thou freely confront one another in mutual effect that is neither connected with nor coloured by any causality. Here man is assured of the freedom both of his being and of Being. Only he who knows relation and knows about the presence of the Thou is capable of decision. He who decides is free, for he has approached the face.
The fiery stuff of all my ability to will seethes tremendously, all that I might do circles around me, still without actuality in the world, flung together and seemingly inseparable, alluring glimpses of powers flicker from all the uttermost bounds: the universe is my temptation, and I achieve being in an instant, with both hands plunged deep in the fire, where the single deed is hidden, the deed which aims at me—now is the moment! Already the menace of the abyss is removed, the centreless Many no longer plays in the iridescent sameness of its pretensions; but only two alternatives are set side by side—the other, the vain idea, and the one, the charge laid on me. But now realisation begins in me. For it is not decision to do the one and leave the other a lifeless mass, deposited layer upon layer as dross in my soul. But he alone who directs the whole strength of the alternative into the doing of the charge, who lets the abundant passion of what is rejected invade the growth to reality of what is chosen—he alone who “serves God with the evil impulse” makes decision, decides the event. If this is understood, it is also known that this which has been set up, towards which direction is set and decision made, is to be given the name of upright; and if there were a devil it would not be one who decided against God, but one who, in eternity, came to no decision.
Causality does not weigh on the man to whom freedom is assured. He knows that his mortal life swings by nature between Thou and It, and he is aware of the significance of this. It suffices him to be able to cross again and again the threshold of the holy place wherein he was not able to remain; the very fact that he must leave it again and again is inwardly bound up for him with the meaning and character of this life. There, on the threshold, the response, the spirit, is kindled ever new within him; here, in an unholy and needy country, this spark is to be proved. What is called necessity here cannot frighten him, for he has recognised there true necessity, namely, destiny.