This, along with Soil Festivities, is a distinct break from his earlier works. This one opens with a gong, agitated rhythm, punctuated theme followed by a thunderous intense (synthetic?) wordless latin-like syllabalic chorus-like voices on top. I don't see any vocal attributions to a single person let alone a whole collection of voices, so I assume it is some pretty sophisticated synthesizer stuff. Nevertheless, it could be real humans not listed in the credits. In other movements, in addition to the chorus voices, there are lyrical passages in the alto/tenor range with similar wordless syllabalic nature that I also assume are synthesized.
Throughout the movements (6 of them) Vangelis explores themes and motifs ranging through lyrical, light, majestic, dark, brooding, abrupt, agitated and thunderous. The material is interesting, complex and rich. If you're looking for elevator/supermarket/reception/on-hold fluff, then this is not the place to find it.
Its tensions never get strident or dissonant. If you are familiar with orchestral works, then, by comparison, the intensities and tensions don't reach the levels found in Ralph Vaughan Williams' 4th or 6th symphonies, Hector Berlioz's Symphonie Fantastique or Gustav Holst's Planets. You won't need therapy and it won't wear you out.
If you listen to all the movements in one sitting, the last movement will give you some well placed light etherial majestic relief and closure to the set of movements.
