The Dweller on the Threshold refers to a purported invisible and possibly malevolent entity that attaches to a human being. The term was first used by Bulwer-Lytton in his novel Zanoni.
In theosophical literature, Helena Blavatsky describes it as the discarded astral double of an individual in a previous life that may not have fully disintegrated yet when that individual is reborn. Thus the dweller will be drawn to the new incarnated personality due to their affinity. Sometimes this entity is also called Guardian of the Threshold.
Another explanation is that provided by Alice Bailey on esoteric astrology, "From ancient recesses of the memory, from a deeply rooted past, which is definitely recalled, and from the racial and the individual subconscious (or founded and established thought reservoirs and desires, inherited and inherent) there emerges from individual past lives and experience, that which is the sumtotal of all instinctual tendencies, of all inherited glamours, and of all phases of wrong mental attitudes; to these, (as they constitute a blended whole) we give the name of the Dweller on the Threshold. This Dweller is the sumtotal of all the personality characteristics which have remained unconquered and unsubtle, and which must be finally overcome before initiation can be taken. Each life sees some progress made; some personality defects straightened out, and some real advance effected. But the unconquered residue, and the ancient liabilities are numerous, and excessively potent, and - when the soul contact's adequately established - there eventuates a life wherein the highly developed and powerful personality becomes, in itself, the Dweller on the Threshold. Then the Angel of the Presence and the Dweller stand face to face, and something must then be done. Eventually, the light of the personal self fades out and wanes in the blaze of glory which emanates from the Angel. Then the greater glory obliterates the lesser. This is, however, only possible when the personality eagerly enters into this relation with the Angel, recognises itself as the Dweller, and - as a disciple - begins the battle between the pairs of opposites, and enters into the tests of Scorpio. These tests and trials are ever self-initiated; the disciple puts himself into the positive or conditioning environment wherein the trials and the discipline are unavoidable and inevitable. When the mind has reached a relatively high stage of development, the memory aspect is evoked in a new and conscious manner, and then every latent predisposition, every racial and national instinct, every unconquered situation, and every controlling fault, rises to the surface of consciousness, and then - the fight is on."
"Two factors tend to bring this about: the slow moving forward of the innate conscience into greater control, and the steady development of the 'fiery aspiration' to which Patanjali (The Light of the Soul, Book II, Sutra I, Page 119) makes reference. These two factors, when brought into living activity, bring the disciple into the center of the burning ground which separates the Angel of the Presence from the Dweller on the Threshold. The burning ground is found upon the threshold of every new advance, until the third initiation has been taken." - The Rays and the Initiations, Alice Bailey
It is interesting in this light that Hugh Shearman in a rather interesting article draws a correlation between the dweller and the mythical dragon that hides some kind of aspirational figure, like a beauty, an imprisoned princess or even a hidden treasure. He goes on to suggest that the dweller is some kind of vanity, spiritual or otherwise, that precedes a fall. This view perhaps minimises the import of the dweller and its impact upon the disciple approaching the gate of initiation.
Nevertheless, the Dweller on the Threshold is seen in contrast to the Solar Angel, both of which need to be cast aside for the disciple to walk through the gate of initiation. It is said that the dweller arrives at full potency prior to taking the third initiation. This makes sense as it is in the third initiation that the disciple enters into life and also overcomes illusion.
According to Bailey, triumph over the dweller leads to initiation, or an entry into a greater measure of life. This is referred to as lifting the first veil.
Astrologer Liz Greene, in "Saturn a New Look at an Old Devil", offers her opinion that Saturn rules the dweller on the threshold experience. Alice Bailey in Esoteric Astrology suggests that Mars and Saturn are involved in the third initiation, the initiation where illusion is finally overcome.
The three signs that are said to deal with the fusion of the dweller and the angel of the presence are Scorpio, Sagittarius and Capricorn.
Van Morrison, who cites his interest in Theosophy in the song "Rave on John Donne" (see Inarticulate Speech of the Heart), refers to himself as a "Dweller on the Threshold" in the song of that name on the album Beautiful Vision.
"Dweller on the Threshold" is also a song on the 1993 Time Machine album by guitarist Joe Satriani and the title of a 2006 release by Latin hard rock band Tribe of Gypsies.
The term "Dweller on the Threshold" is also spoken of in the seminal TV show, Twin Peaks, towards the conclusion of the series. It is mentioned in the context of discussion relating to the "black lodge" and the "white lodge". Particularly, the character Hawk in Twin Peaks Season 2, refers to the Dweller on the Threshold when discussing the inhabitants of the black lodge.
In the novel Blood of Amber from Roger Zelazny's Chronicles of Amber, Corwin's son Merlin encounters a being of primal chaos named Scrof who calls itself a Dweller on the Threshold, guarding the passage to the Keep of the Four Worlds.