Helena Blavatsky on Reincarnation

“If reason has been so far developed as to become active and discriminative, there is no reincarnation on this earth, for the three parts of the triune man have been united together, and he is capable of running the race. But when the new being has not passed beyond the condition of monad, or when, as in the idiot, the trinity has not been completed, the immortal spark which illuminates it, has to reenter on the earthly plane as it was frustrated in its first attempt. Otherwise, the mortal or astral, and the immortal or divine, souls, could not progress in unison and pass onward to the sphere above. p. 352”

“We will now present a few fragments of this mysterious doctrine of reincarnation — as distinct from metempsychosis — which we have from an authority. Reincarnation, the appearance of the same individual, or rather of his astral monad, twice on the same planet, is not a rule in nature; it is an exception, like the teratological phenomenon of a twoheaded infant. It is preceded by a violation of the laws of harmony of nature, and happens only when the latter, seeking to restore its disturbed equilibrium, violently throws back into earth-life the astral monad which had been tossed out of the circle of necessity by crime or accident. p. 351”