Why both are necessary for the beauty of the building
Here is the fifth in the series of short videos by Denis McNamara. Denis is on the faculty of the Liturgical Institute, Mundelein; and his book is Catholic Church Architecture and the Spirit of the Liturgy. Scroll to the bottom if you want to go straight to the video!
Here he distinguishes between two similar, but crucially different ways in which the building is made beautiful - 'decoration' and 'ornament'. The two words are interchangeable in common parlance, he is using them here as technical terms that been developed by architects in order to be able to describe two complementary aspects of a building that are necessary for its beauty.
In the way Denis describes them decoration is a 'poetic', that is beautifully applied adornment that reveals the structural elements of the building. This is to be distinguished from the modern architect's desire to show the structural elements literally, almost brutally, without regard for beauty. The columns used in neo-classical architecture, for example are designed to reveal beautifully their load bearing function.
The church above is a neo-classical design in Poland, while the building below is an 18th century civic building from York in England that clearly points to and is derived from the church architecture.
As we will see, while one would not be surprised to see similar decoration on the two buildings. We would expect to see different ornament. That is because ornament is an enrichment that tells you the purpose of the building. A cross on a steeple, for example, is ornament as it reveals the buildings theological purpose. The cross of St George (the patron saint of England) on the York building tells Englishmen that this is a civic building...although ironically, this is also the Resurrection flag (although as an Englishman I didn't know this until I converted!).
Decoration and ornament are both necessary for a beautiful building because they contribute to the form in such a way that it tells us what this building is. Beauty, remember, is the radiance of being: a property of something that communicates to the observer what he is looking at.
In the flying buttresses of gothic architecture, it occurs to me, this distinction between decorative and literal in structural elements almost seems to disappear. Architects please feel free to contradict me if I am mistaken, but these are fully structural and literal in that sense, but they are also built in harmonious proportion. Might this represent the highest ideal for the architecture?
Anyway, here is the link to Denis's talk: