Percy Shelley formulated Mont Blanc at the end of July 1816, when along with Mary Godwin and Claire Clairmont (Mary Godwin's step-sister) he toured the Arve Valley by Mont Blanc; Europe's highest mountain. Percy Shelley was inspired by the scenery surrounding a bridge over the Arve River in the Valley of Chamonix in Savoy, near Geneva, and decided to set his poem in a similar landscape. He wrote that his verse was composed under the immediate impression of the deep and powerful feelings excited by the objects which it attempts to describe; and, as an undisciplined overflowing of the soul, rests its claim to approbation on an attempt to imitate the untamable wilderness and inaccessible solemnity from which those feelings sprang. Later, when describing the mountains in general terms, he wrote, The immensity of these aerial summits excited when they suddenly burst upon the sight, a sentiment of ecstatic wonder, not unallied to madness.