What did John Ruskin mean by imperfection in Gothic art?

In his influential work The Stones of Venice, specifically in the chapter "The Nature of Gothic," John Ruskin identified "imperfection" as an essential characteristic of Gothic architecture.1

Ruskin contrasted this quality with the mechanical regularity found in Neoclassical buildings and modern mass production. To Ruskin, the "imperfection" of Gothic art was a positive attribute because it reflected the creative freedom and artistic fulfillment granted to the individual workman. He argued that true value in an object is derived from the pleasure taken in its creation, asserting that one should not take pleasure in an object that was not itself made with pleasure.1

This perspective formed the basis of Ruskin’s critique of industrial capitalism and served as a foundational principle for the Arts and Crafts movement in the late 19th century.1