This picture of a timber rattler follows the rule of thirds, but it also illustrates the visualization of shapes in a composition.

Obviously a snake is a linear subject that creates curves as it moves. The trick is to capture the right combination of curves to create an effective composition. Note that this curved snake starts roughly at the lower left intersection point and ends at the upper right intersection point. The linear nature of the snakes body contrasts with the round rocks in this composition. The head is in sharp focus and the snake is clearly "in action" hunting. This is the story.