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### Overview of *Origo Regularum Artis Perspectivae* (1680 – 1681)

*Origo Regularum Artis Perspectivae*

In *Origo Regularum Artis Perspecitvae quales sine libro ac Magistro inveni* (LH 35 XI 17 Bl. 19-20), Leibniz analyses the case of the perspective representation of a segment floating above the objective plane. Just like in other manuscripts about perspective, similar triangles are used to establish relations between different line segments, but this time the terminology used by Leibniz in similar writings, for example the use of “inclinatio” and “declinatio” in Punctorum relatio to indicate how far a given point stands with respect to an established principal point, is substituted here with a terminology taken from geography (“imitatione Geographorum”): the distance between the eye and the Tabula will be called “longitude of the eye”, and with respect to an objective point, the distance to the left or to the right from the principal point will be called “latitude of the object”, while its distance from the tabula will be called “longitude of the object”. In the same fashion, every length which indicates how high an object is with respect to the eye of the spectator will be called “altitude”. We find here one of the most mathematically developed expression of the theorems already present in the other manuscripts, since a proper formula for the general rule of perspective is given. The watermark indicates that the manuscript was written after 1680 – 1681, but no other information can be deduced.