Simplicity

The most powerful photographs employ have only what is needed to clearly convey the intended message.  None of its elements distracts or detracts, but takes the viewer to its subject and helps tell story to be portrayed about the subject.  I title my photographs, but only because I like to.  A title should not be a crutch to help tell the story, only to reinforce what the viewer is already seeing and thinking.  Do not confuse simplicity with having a single element working alone.  Although some exceptional photographs have a single element, many also have multiple elements working together in harmony to take the viewer to its message.

Single Subject

A photograph should have a single subject (although a single subject may be more than one object, person, animal, etc.).  Multiple subjects compete for attention and detract from each other.  None of them "win."  The classic photograph with multiple, competing subjects is the one of a group of people standing in front of a scenic area, monument building or some other subject of interest facing the photographer.  It is both a group portrait and a scenic or architectural photograph.  In the effort to capture both, neither wins.  It would be better to capture the venue (location) of interest with a recognizable person of interest doing something related to the venue.  This can be posed or candid.  Each builds on the other and it becomes a single subject.  Or, if the subject is the person (or people) an recognizable scene can be used as a backdrop for portraiture, but the trick then is to have the backdrop out of focus, low contrast, or combination of the two while the person (people) remain in focus and higher contrast.  Sometimes this requires ingenuity in selecting the "Point of View" (POV) so the subject is recognizable and enough of the venue is recognizable also.  Even then it is still easy to end up with two competing subjects.  The more the person (people) are interacting with the venue, the better, because it builds the two pieces into a single subject.

Art and Aristotle

Having a single subject does not mean the photograph cannot be multi-leveled.  Again, some of the most powerful photographs are very singular in subject and the level at which it is portrayed.  Equally powerful are photographs that use the multiple levels working together to convey a fuller, richer story about the subject.  Yet others will only hint at the story and leave the rest as a mystery for the viewer's imagination.  One of Aristotles better known books is his Metaphysics.  It is a seminal work on philosophy.  The book it followed, Physics (meta means above, after, or beyond in Greek depending on context), was also a seminal work that stood unchallanged for centuries until a few fellows like Galileo, Kepler and Sir Isaac Newton came along.  They showed that Aristotle was close but not quite right about Astronomy and Analytical Mechanics (physical motion).  It is now a cast off work which is sad, because it contains some valuable concepts for examining the physical universe.  (Note that Sir Isaac Newton didn't quite have it completely right either, which made Albert Einstein famous when he corrected a few things.)  One of the valuable "meta-thinking" concepts (how to approach thinking about things) in Aristotle's Physics, Book II, Chapter 3 is his four aitiai.  Aitiai translates roughly to causes which can be used to describe the physical objects we observe:

1. "Material cause;" what the object is made of.
2. "Formal cause;" its structure, shape and form; what it looks like.
3. "Efficient cause;" a poor translation to English because it relates to the object's beginning; how it came to be (or how it was built); the "actions" that created it or "context" that created a need for it and prompted its creation.
4. "Final cause;" (Greek "telos"); an object's "purpose" or "end" or "goal" and explains what it does or intends to do.

The first two do not require anything but the object itself; the third can usually be determined from the object itself, but sometimes not and can require knowing the environment in which it was created.  The fourth requires the object's current context or environment.  Without an environment in which to interact, there is no telos!

If you have gotten this far without hitting the "Back" button, great.  How can a photographer use this concept?  These give some levels to consider in how the subject will be portrayed.  The photograph can be used to visually convey one or more of the subject's four aitiai.  Which depends on what the photographer intends.  The most powerful photographs will convey only those the photographer wishes.  The rest are excluded to leave them as a mystery or prevent them from being a distraction.  An image that captures only texture will convey the "material cause."  One that shows only a sihlouette conveys a "formal cause."  The last two require portrayal of some form of action, interaction or combination of subject elements that the intended viewer rapidly understands how the subject came to be, or what its purpose is.