POLARITIES IN THE EVOLUTION OF MANKIND - GA 197 - Lecture V - Stuttgart, June 24, 1920
https://rsarchive.org/Lectures/GA197/English/RSP1987/19200624p01.html

"The materialistic way of thinking has in more recent times given rise to an idea that is believed by a great many people, namely that the heart is a kind of pump in the human organism that pumps the blood through the organism. This idea of the human heart being a pump comes up in all kinds of variations nowadays. The facts are rather different, however, and should be seen like this: The whole of our rhythmical circulatory system is something alive. It cannot be compared with a system of channels or the like with water flowing through them, water kept circulating with the aid of a pump. Our rhythmical circulatory system, our blood system, is something alive....

It therefore has to be said that materialism has not even managed to get a real understanding of the physical processes relating to the heart in the human organism. The material aspect in particular is completely misunderstood. This is just one of many examples. Material things in particular have found no explanation whatsoever under the influence of materialism. The heart is not a pump. It it something we might regard more as a sense organ incorporated within the human organism to give human individuals a kind of subconscious perception of their circulation, just as the eye perceives colour in the world outside. Basically the heart is a sense organ within the circulatory system, yet exactly the opposite is taught nowadays."

Other lectures by Rudolf Steiner on the nature of the human heart: Steiner lectures on the heart

SPIRITUAL SCIENCE AND MEDICINE - GA 312- Lecture II https://rsarchive.org/Lectures/GA312/English/RSP1948/19200322p01.html

THE HUMAN HEART - GA 212 - 26 May 1922, Dornach
https://rsarchive.org/Lectures/HumHrt_index.html

PSYCHOANALYSIS IN THE LIGHT OF ANTHROPOSOPHY - Lecture V. Connections Between Organic Processes and the Mental Life of Man - 2 July 1921, Dornach
https://rsarchive.org/Lectures/Psych/English/AP1946/19210702p02.html

THE EFFECT OF OCCULT DEVELOPMENT UPON THE SELF AND THE SHEATHS OF MAN
GA 145 - Lecture II - 21 March 1913, The Hague
https://rsarchive.org/Lectures/19130321p02.html

THE GOSPEL OF ST. JOHN (BASLE) - GA 100 - Lecture VII - 22 November 1907, Basle
https://rsarchive.org/Lectures/19071122p01.html

MAN AND THE WORLD OF STARS - GA 219 - THE SPIRITUAL COMMUNION OF MANKIND - V. Spiritual Knowledge is a True Communion, the Beginning of a Cosmic Cult Suitable for Men of the Present Age - 31 December 1922, Dornach
https://rsarchive.org/GA/GA0219/19221231p01.html

THE ORIGINS OF NATURAL - GA 326 - Lecture VIII - 3 January 1923, Dornach
https://rsarchive.org/Lectures/19230103p01.html

NINE LECTURES ON BEES - GA 351 - Lecture VII - 12 December 1923, Dornach
https://rsarchive.org/Lectures/19231212p01.html

MAN — HIEROGLYPH OF THE UNIVERSE - GA 201 - Lecture Six - 18 April 1920, Dornach
https://rsarchive.org/Lectures/19200418p01.html

MAN — HIEROGLYPH OF THE UNIVERSE - GA 201 - Lecture Three - 11 April 1920, Dornach
https://rsarchive.org/Lectures/19200411p01.html

SUPERSENSIBLE KNOWLEDGE - GA 84 - II. Anthroposophy and the Ethical-Religious Conduct of Life - 29 September 1923, Dornach
https://rsarchive.org/Lectures/GA/GA0084/19230929p01.html

COSMIC MEMORY - GA 11 xviii. The Fourfold Man of Earth
https://rsarchive.org/Books/GA011/English/RSPI1959/GA011_c18.html

THE REDEMPTION OF THINKING - GA 74 - Lecture III - 24 May 1920, Dornach
https://rsarchive.org/Lectures/GA074/English/HS1956/19200524p02.html

THE PHILOSOPHY OF THOMAS AQUINAS - GA 74 - Comment V. The Application of Intelligence to the Human Body
https://rsarchive.org/Lectures/GA074/English/PLH1932/ThoAqu_comment5.html

Frank Chester has also done some some amazing work with his 7 sided Chestahedron model of the etheric heart and the 13 sided Decatria model of astral heart, making very similar claims as Steiner, and actually verifying his perspective.

"“The heart is not a pump, but an organ in which etheric space is created, so that the blood is sucked into the heart rather than pumped”.

The Human Heart | Facts about the heart that could change society - https://www.youtube.com/watch?v=yXWk2vNcADo

Frank Chester - Beating Heart Animation - https://www.youtube.com/watch?v=y5E2EI0R7s4

Frank Chester - Heart Lecture - July 2011 -https://www.youtube.com/watch?v=AZdcWRCsaf4

Playlist: https://www.youtube.com/watch?v=_ujfk4fhYi4&list=PL275945C9727A4BB8

Content on John Searl including a few of the books of the law of squares.

Images from a facebook Album by Jason Verbelli about the Searl Technology