The fifth prior of the Grande Chartreuse, Guigo I was esteemed as 'a prior worthy of eternal fame', a prudent man and immensely erudite in both secular and sacred studies. His personal reflections on Holy Scripture take the form of a spiritual journey in which he blends theology and personal experience, daily practicality and ascetic insight, in a way both typical of twelfth-century reformed monasticism and uniquely carthusian.