Man is not fully known. Man is becoming. This means that man in defining what he is has set his own limits. To define him is to close him in to some presumed essence which he is supposed to possess. But this finally destroys man because man's essence is not known.
Man is an open question.
We don't know. The election returns are still out. If the world would come to an end tomorrow, we could theoretically set down what man's essence had been. As long as man remains in existence, however, his essence is not finished. Man first exists , then works out his own essence.