The subtle is a suggestion rather than a complete thought. It is a hint of recognizable shape, a touch of associative line, a colour intimation of mood that hints at extra layers of meaning. Subtle asks the question, what am I seeing here? In Japanese aesthetics, which provides us with perhaps, a more ancient appreciation of the principles of art and beauty, there is the word Yugen:
Real beauty exists when only a few words, or a few brush strokes, can suggest what has not been said or shown, and hence awaken many inner thoughts and feelings.