It might seem like 10,000 days since the last Tool CD. Really, it's only been 1,800 days and change since we heard from Maynard James Keenan and co. on 2001's Lateralus.

Still, a lot can happen in five years. And in Keenan's world a lot has. Professionally, he used his hiatus to record and tour with A Perfect Circle. Personally, we are told, he dealt with the death of his mother, who lived her last 27 years with paralysis from a stroke.

Do the math and you'll see it's that grim time period that supplies Tool's fourth full-length with its title. Listen to 10,000 Days and you'll discover it's Keenan's loss that sets the emotional tone for most of the disc. This is most obvious on the two-part epic Wings for Marie / 10,000 Days, which takes up 17 of the album's 75 minutes. But even they are apparently insufficient to contain Keenan's grief, which washes over to most of the other 58 minutes and manifests itself in draggy tempos, murky sounds and an overall sombre ambience.

It's not a wholesale makeover; fans will recognize the prime-number time signatures, hypercomplex arrangements, precise performances, haunting tones and epic prog-rock grandeur that have helped define Tool since the beginning. But this is a more restrained, measured and controlled Tool than we're used to. Even when the band does crank up and rock out -- as on the swaggering, serpentine The Pot, the tightly wound 11/4 crunch of Right in Two or the tense, hardslugging Rosetta Stoned -- it feels more cerebral and less visceral, if you will. But it is no less compelling. Ditto for Keenan. He's never been the most revealing singer, but this time, he seems especially furtive, lurking into the shadows, daring you to follow him if you seek to unravel his secrets.

Those hoping for the naked aggression and power of the band's earlier days may find 10,000 Days a long, slow slog. But those willing to be drawn into the depths of Tool's dark artistry will find more than enough happening beneath the surface of these songs to keep them occupied for the several hundred days until the next visitation. Failing that, they can pass the hours with the trippy deluxe packaging, which includes built-in stereoscopic lenses and a booklet of magic-eye 3D pix and illustrations.

Track Listing:

1. Vicarious
2. Jambi
3. Wings For Marie (Pt 1)
4. 10,000 Days (Wings Pt 2)
5. The Pot
6. Lipan Conjuring
7. Lost Keys (Blame Hofmann)
8. Rosetta Stoned
9. Intension
10. Right In Two
11. Viginti Tres