De architectura, by Vitruvius

"In all these works, one must have regard to the strength, usefulness, pleasure: the strength, digging the foundation to the the firmest parts of the field, and choosing carefully and without sparing anything the best materials; the usefulness, arranging the scene so that one can get easily served without embarrassment, and distributing everything in a proper and convenient manner; the pleasure, giving the work a pleasant and elegant shape that flatters the eye by the accuracy and beauty of proportions. "

So describes Vitruvius the three main principles of Interior Architecture in his book «De Architectura », written in -25 B.C, and still relevant nowadays. It is the very first written piece in History of humanity treating of architecture and is divided in Ten Books covering every aspect of the antique Rome:

1. Town planning, architecture or civil engineering in general, and the qualifications required of an architect or more modernly the civil engineer
2. Building materials
3. Temples and the orders of architecture
4. 'continuation of book IV'
5. Civil buildings
6. Domestic buildings
7. Pavements and decorative plasterwork
8. Water supplies and aqueducts
9. Sciences influencing architecture – geometry, mensuration, astronomy, sundial
10. Use and construction of machines - Roman siege engines, water mills, drainage machines, Roman technology, hoisting, pneumatics

In the Roman conception, architecture needed to take into account everything touching on the physical and intellectual life of man and his surroundings.

"Architecture is a science that embraces a wide variety of education and knowledge; it knows and judges all the productions of the other Arts. It is the fruit of the practice and theory. The practice is the same design, continued and worked through exercise, which is realized by the act of giving the material to any work, the form shown on a drawing. The theory, however, is to demonstrate, to explain the correctness, the suitability of the proportions of worked objects.Also architects who, in defiance of the theory, come only to the practice, could not reach a reputation commensurate with their efforts. As for those who believed they had enough just with reasoning and literary science, it is the shadow and not the reality they have pursued. Only one whom, like the warrior armed at all points, knows joining theory to practice, achieved their goal as successfully as promptly. "

Vitruvius, thus, deals with many theoretical issues concerning architecture. For instance, in Book II of De architectura, he advises architects working with bricks to familiarise themselves with pre-Socratic theories of matter so as to understand how their materials will behave. Book IX relates the abstract geometry of Plato to the everyday work of the surveyor. Astrology is cited for its insights into the organisation of human life, while astronomy is required for the understanding of sundials.
Vitruvius' work was rediscovered in 1414 by the Florentine humanist Poggio Bracciolini, who found it in the Abbey of St Gallen, Switzerland. He publicized the manuscript to a receptive audience of Renaissance thinkers, just as interest in the classical cultural and scientific heritage was reviving.The rediscovery of Vitruvius' work had a profound influence on architects of the Renaissance, prompting the rebirth of Classical architecture in subsequent centuries. Renaissance architects, such as Niccoli, Brunelleschi and Leon Battista Alberti, found in De architectura their rationale for raising their branch of knowledge to a scientific discipline as well as emphasising the skills of the artisan. Leonardo da Vinci's best known drawing, the Vitruvian man, is based on the concepts of proportion developed by Vitruvius.