Man is, in essence a Spark of the divine Fire, belonging to the monadic world.
To that Spark, dwelling all the time in that world, we give the name "Monad". For the purposes of human evolution, Monad manifests itself in lower worlds.
When it descends one stage and enters the spiritual world, it shows itself there as the triple Spirit, having itself three aspects (just as in worlds infinitely higher the Deity has His three Aspects.)
Of those three one remains always in that world, and we call that the Spirit in man.
The second aspect manifests itself in the intuitional world, and we speak of it as the Intuition in man.
The third shows itself in the higher mental world, and we call it the Intelligence in man. These three aspects taken together constitute the ego which ensouls the fragment from the group-soul.
'Man' as we know him, though in reality a Monad residing in the monadic world, shows himself as an ego in the higher mental world, manifesting these three aspects of himself (Spirit, Intuition and Intelligence) through that vehicle of higher mental matter which we name the 'causal body.'
This ego is the man during the human stage of evolution; he is the nearest correspondence, in fact, to the ordinary unscientific conception of the soul. He lives unchanged (except for his growth) from the moment of individualization until humanity is transcended and merged into divinity. He is in no way affected by what we call birth and death; what we commonly consider as his life is only a day in his life.
The body which we can see, the body which is born and dies, is a garment which he puts on for the purposes of a certain part of his evolution.