The word "Gothic" for art was initially used as a synonym for "Barbaric", and was therefore used pejoratively. Its critics saw this type of Medieval art as unrefined and too remote from the aesthetic proportions and shapes of Classical art. Renaissance authors believed that the Sack of Rome by the Gothic tribes in 410 had triggered the demise of the Classical world and all the values they held dear. In the 15th century, various Italian architects and writers complained that the new "barbarian" styles filtering down from north of the Alps posed a similar threat to the classical revival promoted by the early Renaissance. The "Gothic" qualifier for this art was first used in Raphael's letter to Pope Leo X c. 1518 and was subsequently popularised by the Italian artist and writer Giorgio Vasari, who used it as early as 1530, calling Gothic art a "monstrous and barbarous" "disorder". Raphael claimed that the pointed arches of northern architecture were an echo of the primitive huts the Germanic forest dwellers formed by bending trees together – a myth which would resurface much later in a more positive sense in the writings of the German Romantic movement. "Gothic art" was strongly criticized by French authors such as Boileau, La Bruyère, Rousseau, before becoming a recognized form of art, and the wording becoming fixed. Molière would famously comment on Gothic: