Castor is the four-thousander on Monte Rosa planned as the season’s culminating climb for Giovanni Guasti and his son Pietro. In Pietro’s recollection, the mountain matters not only as a summit but as the setting for a refuge vigil: while the next day’s climb approaches, Giovanni writes in a shared guestbook about the future he imagines for them. Pietro, still struggling with altitude sickness and skeptical of his father’s language about the mountains, reads the same evening very differently.## The planned ascent and its costsCastor was to be the Guastis’ four-thousander that summer. Father and son aimed to climb one such summit on Monte Rosa each year, ending the season high after they had trained. Earlier seasons had taken them to Vincent in 1985 and Gnifetti in 1986; Giovanni regarded these ascents as preparation for more demanding objectives, including crossing the Lyskamm or climbing the rock faces of Dufour. He had consulted a doctor and believed Pietro would eventually outgrow his altitude sickness.The plan was less an adventure for Pietro than a repeated test of endurance. He had continued going onto the glacier, but had become accustomed to feeling ill there, treating the sickness as part of the routine alongside predawn starts, freeze-dried refuge food, and crows calling at altitude. He hated the white landscape and the effort of putting one foot in front of the other before vomiting at the top. At the same time, reaching above four thousand meters gave him pride: each ascent seemed to prove his courage, even when he resented the experience.## The refuge vigil and Giovanni’s guestbookIn Pietro’s memory, Castor is inseparable from the evening in the refuge before the climb. The room held the concentrated anticipation of the following day: Giovanni and Pietro ate pasta with half a liter of wine while nearby mountaineers, ruddy from sun and fatigue, argued. Giovanni liked reading refuge guestbooks. Speaking German and understanding French, he translated entries for his son: climbers returning to a summit after thirty years, thanking God, or lamenting an absent friend. Moved by these traces of other people’s lives, he took up the pen to add his own.When Giovanni stood to refill his carafe, Pietro read what he had written. The entry identified him as a father at the head of the rope with his fourteen-year-old son, and imagined that these would be among his last occasions leading because Pietro would soon pull him up instead. Giovanni also described carrying the memory of their days in the mountains back to the city. The entry made the guestbook more than a record of ascents: it held Giovanni’s hope that the climb would mark a change in their relationship.## Two meanings of mountain lifePietro was not moved or proud when he read his father’s words. They sounded sentimental to him, an idealized mountain rhetoric that did not match their actual lives. If the mountains were such a paradise, he wondered, why did they not stay there? Why had they taken a friend born and raised in the mountains away from that life, and why were they making him live with them in the city? His irritation reached beyond the guestbook to the authority with which his parents had decided what was best for someone else.The difference between father and son was not simply that one loved climbing and the other did not. Giovanni’s entry projected a future in which the two would be companions, sharing the rope and eventually drinking wine over route maps at a refuge. When he returned in high spirits, he poured Pietro another glass. It was the third-to-last day of his holiday, a Friday in August of his forty-sixth year, and he was spending it with his only son. Pietro could see the possibility Giovanni cherished, but at that moment he did not share its confidence.## The climb as a record of memoryLater discoveries give this episode a wider place in Pietro’s understanding of his father’s mountain life. At Grana, he finds Giovanni’s map covered over two decades with a dense web of routes, so marked that it has become almost illegible to anyone else. Its colors distinguish journeys: black for Giovanni, red for Pietro, and green for Bruno. The red accompanies Giovanni to their four-thousanders, while many routes combine black and green. The map does not turn Castor into a simple story of closeness; instead, it records how Giovanni continued to make a life in the mountains with different companions, even as his son remembers the tension within their shared climbs.Pietro also comes to understand Giovanni’s idea that a glacier preserves what summer melts away: it holds the snow—and the memory—of winters past. That image helps him distinguish the father he knew in the city from the man he had glimpsed in the mountains, walking behind him on the paths and drawn to glaciers. Later, the memorial work at the house he builds with Bruno carries that understanding into a shared, physical place: Pietro carves Giovanni’s name and dates into the rock and connects remembrance with the idea of refuge. Castor’s guestbook is an earlier, more private version of the same act. Giovanni leaves a record of the climb and of the father-son future he hopes for; Pietro’s later reading preserves both that hope and the distance that, on the refuge’s eve, kept him from accepting it.