Beauty is the quality of something that pleases or delights the senses, and which has an effect upon the mind. It is an important component of human psychology, and it is a fundamental part of human culture, as well as the arts.
Historically, most philosophical accounts of beauty treated it as an objective quality: they located it in the beautiful object itself or in its qualities. Some, such as Augustine in De Veritate Religione and Plotinus in the Enneads, connect it to a response of love and desire, but they also locate beauty itself in the realm of the Forms.
Modern philosophy, beginning with Alexander Gottlieb Baumgarten in the seventeenth century and Immanuel Kant in the eighteenth century, moved away from ontology towards a more autonomous discipline called aesthetics. This shifted the emphasis from the ontological components such as truth, goodness, love, and being to the human sensibility of these qualities.
Many philosophers, including Santayana, saw beauty as a sort of pleasure; in other words, as a pleasant sensation, an experience that has an emotional effect on the mind. The pleasure, which is often described as a kind of hedonism, derives not from the ‘beauty’ of the object itself but from the way in which the object induces a certain emotional reaction in the observer.
For example, a painting of the cliffs at Mont Saint-Victoire is considered to be beautiful because it depicts an idealized landscape that is pleasing to the eye. However, a photograph of the same landscape may be considered to be less attractive.
The classical conception of beauty is that it should instantiate definite proportions and relations among parts, which should be harmoniously balanced in order to make a comely total. This conception was influenced by the ancient philosophy of the Greeks and became central in the Renaissance, especially in the Italian Renaissance.
Aristotle held that the beauty of a thing could be judged by its integrity and perfection, or by its due proportions and consonance. He also emphasized the moral quality of the beauty that was perceived, and he held that a person should be “beautiful” only if she were good in every respect.
This view was criticized by Aquinas, who argued that the observant must have some kind of ability on the side of taste in order to perceive and judge beauty accurately. He also argued that the standards of validity of judgments of beauty were intersubjective, and would vary in the long run.
This idea is still present in many of the modern views on beauty. For example, the contemporary German philosopher Max Scheler argues that the definition of beauty in terms of the emotions it induces in the beholder is a better way to describe what is considered beautiful than its objective properties, as seen by Kant. But, unlike the traditional conception of beauty, this account fails to recognize that moral beauty is important in its own right, and it ignores the evident “beauty” of mathematics along with the unparalleled beauty of nature.