Abstract
Why an architect Brunelleschi invented the rules of perspective, the method of painter as defined soon after the invention by L.B. Alberti in his treatise "Della pittura"? The subject of this paper is to make clear the meaning of the invention, that is, the architectural meaning of the perspective method, not as a supplementary but as a proper, practical means for the architectural design. The part I of the paper analysed Manetti's description of the first perspective panel painting the San Giovanni baptistery. The analysis, even though the conclusions of the analysis remain hypothetical from the fact that the panel itself does not exist and the Manetti's description is not systematical, made or showed as clear as possible the fundamental structure of the perspective system applied by the architect. Conclusions are as follows, [1] The visual pyramid of (1 : 1 : 1) ratio, as assumed S.Y. Edgerton Jr, is fundamental. [2] The technical meaning of the size and figure of the panel, "circa mezzo braccio quadro" as described by Manetti, was cleared on the hypothesis of (1 : 1 : 1) visual pyramid.
