The former is perfection, realization, fullness of being; the latter imperfection, incompleteness, perfectibility. According to Hegel, human history strives toward perfectibility, but nature does not. According to Rousseau, these were developed through the innate perfectibility of humanity. They believed in the perfectibility of people and were highly moralistic in their endeavors. Darwin soothed readers that evolution was progressive, and directed towards human perfectibility. The theme of the work is the perfectibility of man by moral means. Equally, human "perfectibility" could explain this change in the nature of the human being. They differed from animals, however, in their capacity for free will and their potential perfectibility. The number "seven" has a special meaning in Biblical sense&colon; it symbolizes human perfectibility. Instead, perfectibility describes how humans can learn by observing others. The idea of human perfectibility had, however, become more comprehensive.