Aesthetics is the area of philosophy which covers the concepts of beauty and art.
There are two basic standings on the nature of beauty: objective and subjective judgement. Subjective judgement of beauty suggests that beauty is not the same to everyone — that which aesthetically pleases the observer is beautiful (to the observer). Alternatively, those partial to the objective description of beauty try to measaure it. They suggest that certain properties of an object create an inherent beauty — such as symmetry and balance. Both Plato and Aristotle supported the objective judgement. Some, such as Immanuel Kant, took a middle path, holding that beauty is of a subjective nature, but there are qualities of beauty which have universal validity.
The classical concepts behind aesthetics saw beauty in nature, and that art should mimic those qualities found in nature. Aristotle's Poetics describes this idea, which he develops from Plato's teachings. Modern aesthetic ideas, including those of Kant, stress the creative and symbolic side of art — that nature does not always have to guide art for it to be beautiful.