I disagree with the statement that says opiate and undertow were just a gateway to aenima and so on. I believe undertow and opiate have to do something with Paul D Amour. I heard a rumor that Justin Chancellor writes a lot of their music. But you have to appreciate every cd for what it is. Undertow and Opiate lean towards a alternative metal album where as the rest of them are pretty progressive.
P.S. I'm going to see tool Sep,26 at the Peterson Event Center in Pittsburgh. It's going to be SWEEEET!!!