Artificial irrigation led to cooperation and the development of a central government that was based on professional knowledge, a rule of hydraulic engineers. The prosperity of everybody depended on a successful administration and a strong central government (cf. Karl Wittfogel's hydraulic hypothesis). Later on, the leading engineer became a sacred king (cf. Henri Frankfort) and a god (Osiris) after death. Ritual and magic formed the germs of the first sciences, of biology and physics. The building of tombs initiated the development of architecture.