William Hogarth wrote his Analysis of Beauty in 1753, during the Age of Enlightenment. Through this captivating text, he tends to define the notion of beauty in painting and states that it is linked, per se, to the use of the serpentine lines in pictorial compositions. He calls it the "line of beauty". His essay is thus dedicated to the study of the composition of paintings, depending on the correct use of the pictorial lines, light, colour, and the figure's attitudes. These timeless concepts have been applied by several artists through the centuries. Paintings from every period have here been chosen to support this demonstration. They allow us to explore the various manners in which beauty can be expressed in painting.