I've just been looking at 'Color Correction' - a volume of the non-commercial colour photography of Ernst Haas. He says somewhere: "For me, photography became a language with which I have learnt to write both prose and poetry."
That is a very interesting idea - that photography can be divided into the equivalent of verse and prose. Perhaps he meant that his commercial work was the prose side, some kind of linear process which marched relentlessly to a predictable conclusion. The poetry would then be something more abstract and affective: images which made their way by association or allusion. It is these latter which make up the volume I have been looking at.
Maybe there is something in the distinction. On the other hand, prose can be just as allusive as poetry and rum-ti-tum poetry can be just as predictable as some prose. All photographs both depict and allude and that is less true of words which tend to direct one's thoughts rather more firmly. In the end EH's distinction can go only so far. The potency of the photograph will always set it apart from words.