This is the follow-up to the first Garbarek/Hilliard album - "Officium".
"Officium" was stunning at the time with it's choral works of achingly beatiful melodies from both the Hilliards and Jan Garbarek. At the same time, some of the saxophone lines were taxing and challenging to the choral lines.
Mnemosyne follows on in the same vein, but adds a different flavour by using both secular and sacred sources, as well as a couple of Jan Garbarek originals. This time though, the choice of choral works means there is a less "sacred" feel to the choral aspects, and the sax lines are much more to the forefront, and more challenging; at times swamping the vocal lines, and seeming discordant. This is no bad thing if you want the challenge, but isn't to everyone's taste.
If I were only buying one of the two, I'd buy "Officium", I find it easier to listen to. If I were buying only one of the two, for a technical modern jazz fan, or someone who understands music in a very technical manner, I'd probably go for "Mnemosyne". If I wanted either performer by themselves, there is a wide selection available, safe in their usual genres.
Mnemosyne is by no means a bad album, I'm happy I have both. I like Jazz, I also like sacred music (and rock, folk, heavy metal, punk, reggae, rockabilly, etc etc etc).
I give Officium 5 stars, and Mnemosyne 3.