The laws of principality and unity, harmony and balance, must always be observed. The picture should tell one story, and only one. - Arthur Hammond

...but the fundamental element of picture-making is the cutting of the picture-space by lines or edges of tones, and this is what is known as "spacing".

...I want to make it clear that the success of a picture, as a picture, does not depend upon topographical interest of the subject, but on the ability of the photographer to convey impressions of beauty or interest by his manner of treating it.

Lines have expression, and by the use of lines alone we can suggest impressions.