'The Analysis of Beauty' is an 18th-century book by William Hogarth, an artist and writer, which explores his theories on beauty and grace in a way that is accessible to everyone. Hogarth's main theory is the Line of Beauty, which consists of an S-shaped curve that creates movement and liveliness in a piece of art. The book also covers six principles of beauty, including fitness, variety, regularity, simplicity, intricacy, and quantity. Hogarth's work was a critique of the fashionable taste of his time, and he aimed to democratize the understanding of art.