The video below from the Tate museums, explains how The Kiss was originally conceived as a detail in an early version of Rodin’s The Gates of Hell, a monumental work that preoccupied the artist for the last 37 years of his life. The Kiss depicts the fateful embrace of Francesca and Paolo, adulterous lovers from Dante’s Inferno.
Rodin developed the theme of The Kiss in plaster and terracotta before creating a marble version for the French government in 1888. That version is now on display at the Musée Rodin in Paris. The version featured in the Tate video was commissioned in 1900 by an American art collector living in England, and is now part of the permanent collection of the Tate Modern in London.