The concept of a collective antahkarana cannot be easily found in the theosophical literature. Yet the actual existence of collective connections to higher realms of consciousness is not difficult to perceive.
According to the “Theosophical Glossary”, the Sanskrit word Antahkarana or Antaskarana means “the path or bridge between the Higher and the Lower Manas, the divine Ego and the personal Soul of man”. 
Seen in itself, the concept refers to the individual life. But there is no actual separation between different beings. Individual and collective lines of evolution interact with each other all the time at the various levels and sub-levels of consciousness. Human individuals influence each other, mutually stimulating or hindering their connections with their higher selves. In every society there are cultural characteristics, collective activities and even institutions that enhance or endanger the working of individual Antahkaranas.
There is also the collective impact caused by the work of each Messenger of Truth. History, ancient and modern, has shown that the individual lives of highly evolved beings have a definite impact on the collective karma, sometimes over long periods of time. They create bridges towards higher streams of consciousness which affect millions of lives; and these lives, in their turn, gradually change the whole of humanity.
As one calmly thinks about this, a wide, abstract, flexible concept of “collective antahkarana” may start to make sense. The life of H. P. Blavatsky in the 19th century is an example of that. Her tremendous impact in human history was documented by Sylvia Cranston.  H.P.B.’s teachings and the school of thought she left in the world are permeated by magnetism coming from higher sources and pertaining to abstract levels of consciousness.
The quality and importance of the higher magnetism emanating through H.P. Blavatsky’s work derives from the fact that she was a direct agent of those sages who are called Immortals by Taoism, Rishis or Jivanmuktas by Hinduism, Arhats by Buddhism, and raja-yogis or Adepts by the esoteric philosophy.
The presence and influence of her writings is a central part of the present-day cultural bridge between human civilization and higher levels of consciousness. H.P.B.’s work also constitutes a subtle, higher-manasic “bridge” to future stages of human development. Such a vibrating current in the ocean of life does not include all of the theosophical movement, though, for a large part of the movement is only nominally theosophical. HPB said so in her own time, and so did her Masters. It is easy to understand that no external label can ever guarantee the authenticity of anything.
As H.P.B. worked for mankind, she was surrounded by a powerful magnetic field. Those energies were impressed in nearly everything she did, said or wrote. Her aura transmitted a bit of it into every situation she was involved in. Her direct disciple Alice Cleather described the impact H.P.B. caused on people and on society:
“Like a Light brought into a dark place full of the creatures which ‘love darkness rather than light’, so was the real H.P.B. Instantly, like moths attracted to a lamp, all the denizens of this dark place which is our earth - the realm of illusion (...) - were irresistibly attracted round her. Not only did they obscure the Light - this they did abundantly - but finally in 1891 they put it out; i.e., it was withdrawn from our midst, returning to the realm from whence it came.” 
Alice Cleather wrote about the moment when she first saw H.P.B. physically, in Lansdowne Road, London, 1887:
“When we were ushered into the well-known double drawing-room on the ground floor my attention immediately became riveted on the figure of a stout, middle-aged woman seated with her back to the wall before a card table, apparently engaged in playing Patience. She had the most arresting head and face I had ever seen, and when she lifted her eyes to mine, on Mr. Keightley presenting me, I experienced a distinct shock as her extraordinarily penetrating blue eyes literally ‘bored a hole’ through my brain. She looked steadfastly at me for a few seconds (most uncomfortable ones for me) then, turning to Mr. Keightley, remarked indignantly: ‘You never told me she was like this!’ - absolutely ignoring his assertion that he had repeatedly done so. Exactly what ‘like this’ indicated I never subsequently discovered. Such was my introduction to the greatest incarnated Soul of our times; but at that early date I realised nothing more than that she took one’s breath away; and that ‘life was never the same again.’ From that moment I became her devoted disciple...” 
The enlightening impact of H.P.B.’s work on human evolution exposes and displaces various levels of routine, and the reaction against it has been strong. Since the 1880s, theosophists have had to defend the teacher and the teachings against numerous attacks coming from dogmatic religions and also from inside the theosophical movement. Life is probatory, and every student of theosophy has to face tests. From Pythagoras of Samos to Apollonius of Tyana, as from Alessandro Cagliostro to H.P.B., attacks against Messengers of Truth always threaten the sources of human inspiration and aim at damaging the cultural and occult bridge to the higher realms.
The idea of collective antahkarana is equivalent to the symbolical image of Jacob’s ladder in the Bible. Genesis, 28:11-13, tells us the story of Jacob’s Ladder thus:
“At sunset he came to a holy place and camped there. He lay down to sleep, resting his head on a stone. He dreamt that he saw a stairway reaching from earth to heaven, with angels going up and coming down on it. And there was the Lord standing beside him.”
The Angels are the Messengers of the “Gods” among human beings. They inhabit the Divine Ladder, the eternal and Unbroken Link between Masters and Men.
Another metaphor in the theosophical literature is undoubtedly related to this same occult fact. In “The Voice of the Silence”, a higher aspect of the collective Antahkarana is described not as a symbolical Ladder, but as a “Guardian Wall”. In the Fragment III of that book, we see the description of the path of sacrifice trodden by great souls:
“Self-doomed to live through future Kalpas , unthanked and unperceived by men; wedged as a stone with countless other stones which form the ‘Guardian Wall’, such is thy future if the seventh Gate thou passest. Built by the hands of many Masters of Compassion, raised by their tortures, by their blood cemented, it shields mankind, since man is man, protecting it from further and far greater misery and sorrow. Withal man sees it not...”
In an explanatory note, H.P.B. writes about the “Guardian Wall”:
“It is taught that the accumulated efforts of long generations of Yogis, Saints and Adepts, especially of the Nirmanakayas, have created, so to say, a wall of protection around mankind, which wall shields mankind invisibly from still worse evils.” 
Such a complex notion transcends all metaphors used to describe it.
The image of a Guardian Wall and the idea of a ladder to heaven, as that of a collective Antahkarana, are symbols of the multidimensional process by which humanity has access to divine guidance and inspiration. In “Light on the Path”, a classical work, a reference is made to the same basic fact:
“When you have found the beginning of the way the star of your soul will show its light; and by that light you will perceive how great is the darkness in which it burns. Mind, heart, brain, all are obscure and dark until the first great battle has been won. Be not appalled and terrified by the sight; keep your eyes fixed on the small light and it will grow. But let the darkness within help you to understand the helplessness of those who have seen no light, whose souls are in profound gloom. Blame them not - shrink not from them, but try to lift a little of the heavy karma of the world; give your aid to the few strong hands that hold back the powers of darkness from obtaining a complete victory.” 
Indeed, afew strong hands of Adepts, Messengers and Disciples do keep an open connection between the eternal wisdom and the common karma of our humanity. H.P.B.’s life was dedicated to enhance this living connection. In May 1891 the last words she spoke before dying revealed that she saw this “occult ladder” between Masters and Men as a matter of great importance for her as an individual. HPB’s last words are recorded in a text published in 1894:
“In 1890 the Headquarters was moved to 19 Avenue Road; the following year H.P.B. left us and her last message for the Society was given to Mrs. [Isabel Cooper-] Oakley the night but one before she died. At three a.m. she suddenly looked up and said ‘Isabel, Isabel, keep the link unbroken; do not let my last incarnation be a failure’.” 
This link is a global connection between the higher and the lower.
In her biography of H.P.B., Sylvia Cranston comments another aspect of her final words:
“By ‘last’ she apparently did not mean her final incarnation, as that would be contrary to one of the basic teachings of The Voice of the Silence, epitomized in the‘Pledge of Kwan Yin’, the Buddhist Goddess of Mercy: ‘Never will I seek nor receive private individual salvation; never will I enter into final peace alone; but forever and everywhere will I live and strive for the redemption of every creature throughout the world’.” 
This suggests that the individuality once known as “H.P.B.” would not cease to actively help mankind. The content of the Kwan Yin’s Pledge is strikingly similar to the description of the Guardian Wall in “The Voice of the Silence”, which was quoted a few paragraphs above:
“Self-doomed to live through future kalpas, unthanked and unperceived by man, wedged as a stone with countless other stones... ”
The impact of HPB’s work for humanity, certainly including several incarnations of the spiritual soul of which she was but one life, is a significant element of our present-day collective antahkarana. It will constitute a stone, among countless others, in the long-term and time-honoured Guardian Wall.
Theosophical literature has a number of references to the collective bridge linking mankind to higher levels of consciousness.
In “The Key to Theosophy”, H.P.B. wrote about the Esoteric School she founded in 1888. In her London days, this School had an “inner group”, and notes were taken during its meetings. In the report of the Inner Group meeting of November 12th, 1890, we can see:
“H.P.B. said that the Inner Group was the Manas of the T.S, the E.S. was the Lower Manas, and the T.S. the quaternary.” 
As Manas and Lower Manas contain Antahkarana, H.P.B. was implying that the theosophical movement, the E.S. and the I.G. of her day formed something similar to a collective Antahkarana.
In the Mahatma Letters, one can read these words from one of the Adept-Teachers:
“Tho’ separated from your world of action we are not yet entirely severed from it so long as the Theosophical Society [meaning, the Theosophical Movement] exists.” 
Here, again, the theosophical movement is seen as a bridge. Another reference can be found in a letter by H.P. Blavatsky. She writes:
“W.Q. Judge is the Antaskarana between the two Manas (es), the American thought & the Indian - or rather the trans-Himalayan Esoteric Knowledge.” 
H.P.B. saw the role played by William Judge in the making of a permanent spiritual link between the Americas and the eastern esoteric philosophy.
The wider, global “collective ladder” needs constant occult attention. Building, sustaining and expanding it is a long term process. The task includes a current of “messengers” of various degrees of development, who come century after century. Sometimes the same soul comes once and again at brief intervals. H.P.B. hinted in “The Secret Doctrine”:
“In Century the Twentieth some disciple more informed, and far better fitted, may be sent by the Masters of Wisdom to give final and irrefutable proofs that there exists a Science called Gupta Vidya; and that, like the once-mysterious sources of the Nile, the source of all religions and philosophies now known to the world has been for many ages forgotten and lost to men, but is at last found.” 
In the 20th Century, she wrote; and the Messenger didn’t show up. But Masters do not have to give to the public the exact dates and timing of what they do for mankind.
We should be content with the small elements of information we are able to gather about this work. We have H.P.B.’s word that there may be another Messenger. We are not in a position to complain if we have to wait for another 100 or 200 years. We must be willing to fulfil whatever task is in front of us, while understanding that our lifetime is part of a much wider perspective.
William Judge wrote in an article entitled “The Closing Cycle”:
“H.P. Blavatsky has clearly pointed out in the ‘Key’, in her conclusion, that the plan is to keep the T.S. alive as an active, free, unsectarian body during all the time of waiting for the next great messenger, who will be herself beyond question.” 
That plan every student can help fulfill.
If Judge’s words are true, the same monad who animated “H.P.B.” may come again sooner or later and will then have to use at least part of her old public and private skandhas or karmic heritage in order to help human kind. Indeed, while referring to the theosophical movement, H.P.B. wrote:
“It has my magnetic fluid”. 
And Theosophy teaches that Karma is about affinities.
As long as no new Messenger or Messengers appear in a way that is easy enough for all to see, the students of theosophy are the caretakers of the work-to-be-continued. Each student is a Messenger within the limits of his own possibilities. For many of them, it can be a stimulating task to help defend and preserve - for an unknown amount of time - those karmic patterns of the heart of the esoteric movement which a greater Messenger will, sooner or later, have to face, select, adapt and use again, adding new strength to the long term progress of mankind as a whole. Such karmic patterns and tools include the teachings of modern theosophy.
 “The Theosophical Glossary”, by H. P. Blavatsky, The Theosophy Co., Los Angeles, 1990.
 See especially the Part Seven of the book “HPB - The Extraordinary Life and Influence of Helena Blavatsky, Founder of the Modern Theosophical Movement”, by Sylvia Cranston, published by Jeremy P. Tarcher/Putnam Books, New York, USA, 1993, 647 pp.
 “H.P. Blavatsky, Her Life and Work for Humanity”, Alice L. Cleather, Thacker, Spink & Co., Calcutta, 1922, 124 pp., see p. 72.
 “H.P. Blavatsky As I Knew Her”, Alice L. Cleather, Thacker, Spink & Co., London, 1923, 76 pp., see p. 04.
 Kalpas: Cycles of Ages.
 “The Voice of the Silence”, translated and annotated by H. P. Blavatsky, Theosophy Co., Los Angeles, 1987, p. 74. In the TPH/Quest Edition (1992), see “The Voice of the Silence”, p. 68; the explanatory note (number 28) is at page 94 of TPH edition.
 See the Note referring to Rule 20, in the part I of “Light on the Path” (Theosophy Co.), a book transcribed by Mabel Collins.
 “The Path” magazine, July 1894, volume IX, page 124. Her “last incarnation” was probably not the one she was then closing, but the following one. “Last” could mean “last before liberation from unconscious rebirth”.
 “HPB - The Extraordinary Life and Influence of Helena Blavatsky”, by Sylvia Cranston, 1993, see p. 407.
 “The Inner Group Teachings of H.P. Blavatsky”, Point Loma Publications, 1985, p. 27.
 “The Mahatma Letters to A. P. Sinnett”, T.U.P., 1992, Pasadena, CA, USA, Letter LXXVIII, p. 378.
 “Letters That Have Helped Me”, by W. Q. Judge, Theosophy Co., 1946, pp. 277-278. The sentence is part of a letter written by H.P.B. Canadian author Ernest Pelletier reports that the magazine “Theosophia” published a reproduction of the original letter in its volume 7, March-April 1951, pp. 8-9. See “The Judge Case, a Conspiracy Which Ruined the Theosophical CAUSE”, by Ernest Pelletier, Edmonton Theosophical Society, Edmonton, Alberta, Canada, 2004, page 27 - Part I, Chronology.
 “The Secret Doctrine”, H. P. Blavatsky, The Theosophy Co., Los Angeles, 1982, facsimile edition, volume one, p. XXXVIII.
 “The Closing Cycle”, in “Theosophical Articles”, by W. Q. Judge, Theosophy Company, Los Angeles, 1980, vol. II, p. 153. The same article is in the book “The Heart Doctrine”, W.Q. Judge, Theosophy Co., Bombay (Mumbai), India, 1977, p. 40.
 See “Theosophical Articles”, H. P. Blavatsky, Theosophy Co., Los Angeles, 1981, volume I, lower half of p. 120. The statement is also quoted at the book “H. P. Blavatsky, A Great Betrayal”, by Alice Leighton Cleather, Thacker, Spink & Co., Calcutta, 1922, 96 pp., p. 02.
An initial version of the article “The Guardian Wall That Protects Mankind” was published at “The Aquarian Theosophist” in January 2006, pp. 25-30, under the title “H. P. Blavatsky And The Guardian Wall”. It was revised by the author in October 2011. Its illustrations are photos of D. Pedro Segundo Fortress, in Caçapava do Sul, RS, Brazil.
On the role of the esoteric movement in the ethical awakening of mankind during the 21st century, see the book “The Fire and Light of Theosophical Literature”, by Carlos Cardoso Aveline.
Published in 2013 by The Aquarian Theosophist, the volume has 255 pages and can be obtained through Amazon Books.