Blavatsky
Original sense
The monad is the immortal spark — Atma-Buddhi — which journeys through kingdoms of nature (the ‘pilgrim’) and only in the human stage adds Manas, self-consciousness. It is not a personality and has no memory of your childhood. Monads are numberless but finite for this manvantara; she claimed no new ones have entered humanity since mid-Atlantis.
The Monad is a ‘drop’ of the Ocean of Absolute Reality… it is Atma-Buddhi, not the personal soul.
Her monad is closer to a cosmic spark than to a novelistic soul. The stories we tell about ‘my soul’s journey’ are, at best, the autobiography of Manas.