At the same time the mathematicians were able to create curves and curved surfaces with the help of the coordinate system. “… while descriptive geometry encouraged the free orientation of forms in relation to one an-other, Durand’s orthographic projection was used to enforce the frontal and rectilinear. So whatever the defects in Durand’s teaching, Monge’s geometry can hardly be held to ac-count for them.” [6, p.327]. Also today you find this misunderstanding on the role of geometry in architecture if the strong forms are equated with geometry and the organic forms are seen in contrary to geometry. Evans states in his book appropriately: “When architects attempt to escape from the tyranny of geometry, mean-ing by the tyranny of the box, where can they escape to? Either they must give up geometry altogether (which would be exceptionally dif-ficult), or they escape to another, always more complex and demanding geometry, or they do the last while giving the impression of having done the first, …” [6, p.331]. It is not the challenge of geometry to provide a catalogue of eidetic forms for architecture. Geometry rather provides the geometrical un-derstanding of space as a background for archi-tecture. Whereas the Euclidean geometry has its roots in measurements and therefore corre-sponds with the tactile space, the projective geometry corresponds with the visual space and refers to the perception. Evans pleads in in-volving projective geometry in architecture. He states that the indication of the two different kinds of geometry “enable us to see why archi-tectural composition is such a peculiar enter-prise: a metric organization judged optically, it mixes one kind of geometry with the other kind of assessment. Perhaps this is reason enough for the confusion surrounding it.“ [6, p.xxxiii] The development of projective geometry got its impetus from architectural demands. The ar-chitect Brunellschi developed constructive principles for perspectives by using geometrical projection methods. Alberti summarized the results of the research in perspective to a teaching concept. Projective geometry origi-nated from generalizing the use of vanishing points and constructing perspective drawings. Now according Evans there could be new im-pulses for architectural design by looking for the relationship between projection and archi-tecture itself. The projections are operating between things and are seen as transitive rela-tions. The diagram in Figure 9 shows four types of targets: designed object, orthographic pro-jection, perspective and imagination combined with the perception of an observer. The dia-gram is thought by Evans as a tetrahedron, so that the center disappears and all relations are equitable. The routes between the targets can be traveled in either direction.