Burckhardt shows here a summary of what make art sacred, namely being a medium for contemplation, and knowing it's place. Also, sacred art doesn't use a material for what it is not, for example, a rock (to be sculpted) is a static thing, not made to represent movement. A surface (to be painted) is two dimensional - therefore the absence of optical illusions and "tricks".
I have always found the likes of Picasso and others to be highly annoying, seems like I begin to understand now why... This makes me think also of "artists" intellectualizing and explaining their works, when the work itself falls into the dark pit of total subjectivity (I express myself) and individualism (only the one who made it "understands" it, and sometimes they themselves don't). When you stand in front of a Sumerian statue in a museum or see a chinese depiction of a demon, you instantly feel that it is meant to overwhelm you, to scare you sometimes even, no need for an "art critic" to explain anything. Art for art's sake is, in fact, a degeneration and the sign of a lack of center.
From wikipedia : "Ironically, the term [Art for art's sake] is sometimes used commercially. A Latin version of this phrase ("ARS GRATIA ARTIS") is used as a motto by Metro-Goldwyn-Mayer and appears in the circle around the roaring head of Leo the Lion in its motion picture logo." Heh, funny...
The body of this book is interesting and I learned a lot from it, but the author's introduction is the most extraordinary gem. It gave me a much better understanding of the purpose of sacred art than anything I have read before or since.
Livro muito bom, li numa tradução brasileira (Editora Attar).
Os capítulos, pelo o que pude notar, não foram escritos pensando num todo, mais se assemelham a ensaios soltos - o que possibilita uma leitura fragmentária e mais livre:
minha recomendação pessoal é ler os textos em blocos e por regiões (hinduismo/budismo/oriente, cristianismo, e terminando com o texto sobre a arte islâmica, claramente o capítulo com viés mais elogioso).