I heard this today on NPR in Garrison Keillor's Writer's Almanac. It's a quotation from Truman Capote:
Writing has laws of perspective, of light and shade, just as painting does, or music. If you are born knowing them, fine. If not, learn them. Then rearrange the rules to suit yourself.
This is as apt for photographers as it is for writers, especially the part about rearranging the rules to suit yourself.
For photographers, learn the "rules" of composition, exposure, depth of field, perspective, etc. Master them to the point that they become internalized and automatic. Then adapt them and even depart from them to suit the creative calling.