(My real favorite track is Rock I, but Fireball I is my second favorite. It is the only one I can currently select.)
This album is engaging and thought-provoking all while being extremely accessible.
I interpret this album as a record of progress in a brief window of a wizard's magical career.
My way of thinking about this is that each track's music aligns with the spell name and level such that the music describes the process of learning and/or casting each spell at the given level.
The first-level tracks are always busy and exciting, disorganized at first but forming together in the end. This is just like one may imagine learning a new spell: the student is excited and knows the potential of what they are learning, but doesn't really know what they're doing yet. By the time they have mastered the first level, they are able to cast with relative ease.
Additionally, the first levels establish musical motifs that are used in the second and third levels; building as they go. The student knows the inner workings of the spell they have learned, how it "feels" to them.
The second levels are just as exciting, but less busy and more of a smooth experience with some brief jolts of action interspersed. The student is getting better; they experience less trouble when they are learning or casting. The second level tracks are always shorter in playtime than the first, the third always shorter than the second. Not only is the student better at the craft, but they are more efficient and can cast and learn faster.
All of these aspects are true testaments to the wizard's progress: they are getting stronger.
The third levels abstract the first and second levels into the most streamlined, elegant and powerful versions of the motifs in the previous two levels. There is nothing left to learn in this spell path, the wizard is the strongest they can be with the spell. They can cast by muscle memory and do so with power and efficiency.
Don, you fucking genius.