I came across a fascinating piece of music last night, while browsing around on Magnatune: Heinrich Ignaz Franz von Biber's Rosary Sonatas. (Magnatune allows free previews of the entire tracks from all their albums, so feel free to go listen.)
Dating from the 1670s, the rosary sonatas are fifteen baroque instrumental pieces, each one a musical meditation on a decade of the rosary. The collection concludes with a violin solo piece dedicated to the guardian angel.
While the music is clearly baroque in style, the emotional specificness with which some of the mysteries are described by their sonatas seems like something of a much later date. This is added to by Biber's use of selective re-tuning of the violin to achieve different effects in each sonata. The violin starts at a standard turning for the first sonata, and is retuned for each subequent piece, until it returns to standard tuning in the 15th decade. The most extreme re-tuning is shown below, where the center strings are restrung to form a symbolic cross for The Resurrection.
Really interesting music. Unless the baroque bores you, give it a try.