 In his "De architectura" Vitruvius creates a model for the emergence of architecture from nature, according to which the first people would have built their dwellings from vertical forks of branches with branches laid over them.Filarete also takes up this idea in his book "Trattato di architettura", in which he explains the origin of the arch as the first doorway.In the early 16th century similar explanations can be found in the writings of Raphael, among others.