To non-scientific readers, Gessner is best known for his love of mountains (below the snow-line) and for his many excursions among them, undertaken partly as a botanist, but also for the sake of exercise and enjoyment of the beauties of nature. In 1541 he prefixed to his "Libellus de lacte et operibus lactariis" a letter addressed to his friend, J. Vogel, of Glarus, as to the wonders to be found among the mountains, declaring his love for them, and his firm resolve to climb at least one mountain every year, not only to collect flowers, but in order to exercise his body. In 1555 Gessner issued his narrative ("Descriptio Montis Fracti sive Montis Pilati") of his excursion to the Gnepfstein (1920 m), the lowest point in the Pilatus chain.