In his The Analysis of Beauty
(1753), William Hogarth identifies, in contradistinction to “straight lines” and “curved lines,” a “serpentine line” witch he names the “line
of beauty.” The line is verbally articulated also as a “waving line,” “winding line,” and “the line of grace”. According to the theory,
S-shaped curved lines indicate liveliness and activity as opposed to straight lines, parallel lines or right-angled intersecting lines, which signify stillness, death or inanimate objects.