I must warn you against too close study of art to the exclusion of nature and the suppression of original thought . . . Art rules should be a guide only to the study of nature, and not a set of fetters to confine the ideas or to depress the faculty of or iginal interpretation in the artist, whether he be painter or photographer; and a knowledge of the technicalities of art [or photography] will be found the best guide . . . The object [of rules] is to train his mind so that he may select with ease, and, w hen he does select, know why one aspect of a subject is better than another.