The handbooks of medieval philosophy consider Lothar of Segni (1161–1216), pope Innocent III, as a violent misanthropist and obscurantist. The article sheds a new light on the founder of medieval ascetism in Christianity, relating his work with the spiritual and conceptual context of the High and Late Middle Ages and highlighting his key role for the history of (humanistic) ideas. This will reveal an uneasy spirit of ambivalent thoughts, who actually mortified man stressing his misery (miseria humanae conditionis), but simultaneously set the references for a new, prometheic conception of human dignity (dignitas hominis) and, even more, planned – but never accomplished – an optimistic encomium of human being (laudatio hominis). One of the greatest pessimists of western thought attained in potentia the Christian anthropological optimism.