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 1541 he prefixed to his Libellus de lacte et operibus lactariis a letter addressed to his friend J. Vogel of Glarus on 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 .