For many years of my life, I was fascinated by mountains and their tops: drawn upwards by what Joe Simpson nicely calls ‘the inverted gravity’ that peaks exert upon certain people. I climbed and mountaineered – ineptly but passionately – in ranges around the world: Snowdonia, the Lake District, the Cuillins, the Cairngorms, the Alps, the Rockies, the Tian Shan, the Himalayas. All of these expeditions, from half-day to multi month, were centred upon summits. My companions and I would scry our maps, mark the tops we wished to reach, then plan our journeys around those high points. It did not occur to me to explore a mountain without reference to its peak.