The child is father to the man in the sense that his individuality is separate from the individuality of the grown-up into which he turns.
 Theodore Roosevelt, Theodore Roosevelt; an Autobiography (1913). copy citation

Context

“He feels as if that child were not the present he, individually, but an ancestor; just as much an ancestor as either of his parents. The saying that the child is the father to the man may be taken in a sense almost the reverse of that usually given to it. The child is father to the man in the sense that his individuality is separate from the individuality of the grown-up into which he turns. This is perhaps one reason why a man can speak of his childhood and early youth with a sense of detachment. Having been a sickly boy, with no natural bodily prowess, and having lived much at home, I was at first quite unable to hold my own when thrown into contact with other boys of rougher antecedents.” source