The Sense of Beauty by George Santayana was published in 1896 and explores human aesthetics. Santayana writes to express his thoughts on how human ideals about beauty compare with objects of beauty and to identify the characteristics common to things that strike us as beautiful.

Santayana's book is divided into four parts; the first part deals with the nature of beauty. Santayana explains the nature of beauty by expressing it through a definition that considers the origin, place, and elements of beauty as an object of human experience. Such a definition, he says, will enlighten us about our own attributes that sensitize us to the aesthetic appeal of an object.

In the second part, Santayana dwells on the materials of beauty. He posits that every human function must contribute to the sense and appreciation of beauty, though the degree of contribution may vary—our eyes and ears are the most prominent receivers of beauty—and an individual’s age influences their passion for sensory pleasures. A young person’s aesthetic pursuits in moments of leisure may vary from an older person’s, for instance, because an older person’s health and vitality may not permit more vigorous activities.

The third part details the presence of beauty in form. Santayana describes the ways in which sometimes disparate elements come together to create an aesthetically pleasing form. He writes that not all houses made of marble are equally beautiful; aesthetic values depend on how the constituent elements of a shape are used or placed together.

In the fourth part, Santayana attempts to explain how people express beauty, writing that our expression of beauty depends on the choice of words and symbols we use to crystallize our thoughts and expressions. Our thoughts allow us to recognize patterns in beautiful objects and experiences, as well as to discern attributes that are not original to an object but that contribute to presenting a complete whole. A scene of past pleasant experiences, for example, will continue to attract us. Even if, at first glance, we may not be able to appreciate the beauty of a scene in terms of its form and constituent materials, we feel its beauty because it revives memories of past pleasantness in the same or a similar setting.