Blavatsky
Original sense
Atlantis is not a single island that sank in a night, but a chain of landmasses inhabited by the Fourth Root-Race over immense geological time. Its last remnant, Poseidonis, perished more recently. Atlanteans developed both high occult knowledge and black magic; their cataclysm is moral as well as geological.
The Atlanteans were the first purely human, earthly race… they built cities and developed a science which we have lost.
She used Plato, Donnelly, and Hindu Puranic flood myths, then placed Atlantis inside a seven-race, seven-round cosmology. The point was cyclic evolution, not a crystal-city utopia.