J. Piaget wanted to study children to find a key to understanding history of mind, culture, science, and philosophy. The new theory program, called the structural-genetic theory program, developed by the author of this article, is an off-spring of Piagetian theory and follows Piaget's main idea concerning the study of parallels between ontogenetic and historical developments. It maintains the full identity of the child's psyche and that of the adult archaic human being concerning traits and features of the preoperational stage and partially the concrete operational stage, thereby evidencing the total sally of the formal operational stage in the minds of archaic people. The identity of the stage structures is not partially given but rather entirely and implies even the smallest details. The article exemplifies this identity concerning several central issues, such as logic, physical understanding, categories such as causality and chance, animism, personification of plants and animals, belief in magic, metamorphosis, ghosts, and understanding of dreams and myths. Accordingly, there is no difference between ontogenetic stages and the psychogenetic development of humankind throughout history. Historically, humankind has gone through the same stages as children do. The new theory program presents the fundamental theory of the human being as he or she existed in history and peopled archaic, ancient, and medieval societies. Consequently, the world history of culture, mind, worldview, politics, law, science, philosophy, morals, religion, and arts must be reconstructed in terms of stages, a task already accomplished by the new program, at least to a certain extent.