Just re-read his "The Decisive Moment" essay ( in Photographers on Photography ). Couple of quotes I like:
To me, photography is the simultaneous recognition, in a fraction of a second, of the significance of an event as well as of a precise organization of forms which give that event its proper expression.
And,
During the process of enlarging, it is essential to re-create the values and mood of the time the picture was taken; or even to modify the print so as to bring it into line with the intentions of the photographer at the moment he shot it. It is necessary also to re-establish the balance which the eye is continually establishing between light and shadow. And it is for these reasons that the final act of creating in photography takes place in the darkroom.