Blavatsky
Original sense
Atman is not the personal soul. It is the universal Spirit, the seventh principle, identical in every being and only ‘human’ when mirrored by Buddhi. She refused to call Atman ‘my spirit’ as if it were a private possession. Personality (the lower quaternary) is mortal; Atman is not an individual at all.
Atma is no individual property of any man, but the Divine essence which has no body, no form…
The sevenfold key: Atma, Buddhi, Manas, Kama, Prana, Linga-śarīra, Sthula-śarīra. Confusing Atman with the reincarnating ego (higher Manas) or with a guardian angel is, for her, a basic error.