A core idea in the architectural theory of Leon Battista Alberti, as expressed in the De re aedificatoria, is the distinction between “lineament,” the line in the mind of the architect, and “matter,” the material presence of the building. This distinction plays a key role in architectural design throughout the history of Western architecture. As Le Corbusier would say in the twentieth century, “architecture is a product of the mind.” The distinction between mind and matter can be found in Vitruvius, in the distinction between “that which signifies and that which is signified”; at the Accademia di San Luca in Rome, between disegno interno and disegno esterno; or in Peter Eisenman’s distinction between deep aspect and surface aspect in architecture, to name just three examples. There are passages in the De amore of Marsilio Ficino where it seems clear that he is referring to his mentor’s concept of lineament. Lines cannot be called bodies, for example, and beauty can only be a property of matter through arrangement, proportion, and aspect (shape and color), which are products of thought, in the Neoplatonic tradition, as in the idea of beauty described by Plotinus, which can be found in Alberti’s concept of beauty or concinnitas. Plotinus distinguished the shape of the matter of a statue from the shape of the statue in the mind of the artist. I would like to suggest that Alberti knew the Enneads of Plotinus, perhaps as a result of a meeting with Gemistos Plethon and Nicholas of Cusa at the Academy of Palestrina, and through the translation of the Enneads by Marius Victorinus. Alberti’s concept of lineament is a Neoplatonic concept, and it plays an important role in architectural theory. Neoplatonism can also be found in Alberti’s proportioning systems in his architecture, as Ficino called Alberti a “Platonic mathematician.” These propositions have never been advanced, that I know of, and they are fundamental to an understanding of architectural theory.
Hendrix, John S., "Leon Battista Alberti and the Concept of Lineament" (2011). School of Architecture, Art, and Historic Preservation Faculty Publications. 30.