The 2 parts of ATMEN GIBT DAS LEBEN were written several years apart, and frankly they are indeed quite different, though they share a common sensibility I suppose. The first part, "Atmen gibt das Leben", comes across to me as stark and subdued, with the "hiccups" being a kind of time-marker of sorts. The most fascinating part of this section is the way the layers of choral voices navigate around each other in semi-heterophonic phrases. When the choir falls into the ending 4-part harmony phrase, it's a beautiful moment, almost as if air were being let into the static environment created by the slow, droney vocals of the preceding section.
The second part of ATMEN GIBT DAS LEBEN, "Sing ich für Dich, singst Du für mich", is very fascinating for the way Stockhausen writes for small and large groups of choral forces. Each of the solos, duos and trio have their own "situation" and mood, and since the melodic material is very accessible (ie - not 'obviously' serial) these solos are very evocative and expressive. The other really interesting element here is how Stockhausen uses the same Tutti refrain over and over again (in essentially the same canonic structure), but finds ways of making each one unique-sounding through vocal mixtures, layering sequences, dynamic envelopes, coloration from the orchestral forces, etc... All of this is incorporated into a somewhat satirical stage drama disrupted by scored moments of "misunderstandings", and all using a vocal text consisting Japanese Haiku, the writings of Socrates, St. Thomas and, Meister Eckhart, and something about Jesus, Satan and particle physics...
Far in the future, Stockhausen would revisit some of the basic structural ideas of ATMEN GIBT DAS LEBEN in his LICHT opera cycle, especially in the works UNSICHTBARE CHÖRE and DÜFTE - ZEICHEN.
I feel that it could be useful to have a discussion-forum on the music of Stockhausen. There are so many people from all over the world, young and old, learned and eager to get into contact with this musical world: musicologists, composers, musicians, music lovers; people who plan concerts - who write books or have to give lectures and so on. So there should be much stuff, many ideas that we can share. And when we have open questions, there may be people who studied just that and could give a hint or a stimulus.
A problem might be the English language, but i feel that is the only possibility that many people who are interested can participate. And we can exercise tolerance to mistakes!