The Parthenon in Athens is seen as the perfect practical embodiment of these harmonic principles in architecture.
What the ancients called “architecture” was actually the sum total of the technical knowledge of the time. Likewise, for Vitruvius, being an ‘architect’ did not involve merely technical expertise in building design, but also a thorough grasp of arithmetic, optics, history, medicine, law, music, astronomy and geography. All ‘educated people’ would have been expected to have been thoroughly grounded in these subjects.
Vitruvius stated that an architect should focus on three central themes when preparing a building design. These themes were firmitas (strength), utilitas (functionality), and venustas (beauty).
Under the category of venustas (beauty), he distinguished six basic concepts: ordinatio (orderly proportion), dispositio (proper arrangement), symmetria (symmetry), eurythmia (harmony), decor (appropriate appearance), and distributio (appropriate allocation of resources).
Ordinatio, symmetria and eurythmia are different aspects of the same aesthetic phenomenon: ordinatio is the principle, symmetria the result, while eurythmia is the effect upon the beholder. Symmetria was purely an objective appreciation of of a building’s beauty; it implied a certain distancing from the experience. Eurythmia, on the other hand, described the pleasant sensations which seeing symmetria aroused in the spectator. Personal involvement and appreciation were actually reflected back on the building.
These principles could then be applied to artistic virtues and values, and in turn to other aspects of life.