The article explores the question of where the special humanity that is repeatedly attributed to Josef Frank's architecture, and which he himself claimed for himself in a letter from 1961, comes from. The article finds the answer in the era of humanism, which was well known to Frank through his dissertation „Über die ursprüngliche Gestalt der kirchlichen Bauten des Leon Battista Alberti“. According to the thesis, Josef Frank's "human modernism" can be traced back to sources from the 15th century; it is, as it were, a translation of certain principles of humanist thinkers and artists into the 20th century. These principles include, above all, varietas in various nuances. In addition, mediocritas, as it appears in Alberti's work, plays a major role. However, these two principles alone cannot describe the human being that Frank has in mind. Human life in all its fullness is the benchmark for Frank and his human architecture.