The Chanson de Roland (Song of Roland) is the oldest work of French literature to have survived. It is an epic poem dating from the twelfth century, recounting the heroic story of Roland during Charlemagne's war with Muslim Spain.
This scene introduces the theme of lesbianism, and more generally homosexuality, which becomes an important part of the novel in later volumes, especially The Captive and Sodom and Gomorrah.
This passage reveals the link Proust wants to establish in the reader's mind between the memory and art. The narrator's memories of Combray, traced on his mind, are compared to the reproductions of art that his grandmother used to show him. Proust believed that the past could only be regained through art, just as an engraving can capture the essence of a work of art which has now faded and decayed.