The orography of the world, if you think about it, has always influenced man on the division of states, peoples and religions. Man has taken rock and water as a pretext as the best means to assert his sovereignty over a territory. The ridges, the ridges, as well as the rivers, have always created divisions. Me on one side, you on the other. But there are men who follow that sign of division, those who navigate it and those who climb it, uniting two points and being able to look closely or from above at those two different worlds, recognizing their differences and interpreting their affinities. While the navigator descends towards the sea, the mountaineer, going in the opposite direction, aims for the summit of a mountain starting from the bottom, conquering that world suspended between two worlds. Both navigator and mountaineer, perhaps unconsciously, are bearers of peace, they unite, even just with their gaze, those two sides, giving both the same dignity, despite their diversity. The high mountain ridge is the maximum expression of division, but those who travel it have the opportunity to be the ideal symbol of union. Having reached the top, the orographic confluence point of two slopes, the mountaineer meets the man from the other world, different but equal to him, who, due to an arcane attraction, has climbed the opposite ridge. The ridge competes with the wall for the beauty of the mountain. On the face you are protected but exposed to falling rock and ice, on the crest you are exposed to the abyss but protected from the will of the mountain. Two worlds in the mirror, where one ends the other begins. Wall: difficulty, closure, sense of protection. Crest: exposure, vision, vertigo. The meaning of this book is condensed in these last three words. For Marco, the work of a lifetime, the symbol of his mountaineering, a route made up of walls but above all of crests, of these dividing threads that condense into a point of union. An enormous, meticulous, important job to give meaning to a life spent among those rocks and ice.