Why does Steiner relate the larynx to eurythmy?

Rudolf Steiner asserted that "in eurythmy the body becomes larynx". The question came by email: Why the larynx? Why not any other organ such as an ear?

What is so fundamental to speech and eurythmy movement? Was Steiner referring to speech merely as a metaphor for introducing eurythmy to the world? Let him speak for himself -

I would like to say that what we can call the Art of Eurythmy is not made of arbitrarily invented gestures, but has been taken over form a natural movement tendency in the human larynx and its nearby organs, from all the organs that take part in the forming of sounds. These movement tendencies in the larynx and other organs are then transferred to the whole human being. In this silent language of eurythmy, accompanied by speech or music, man as a whole performs like a larynx, so to speak. He becomes a larynx in the movement shown on the stage. In the same way, groups of eurythmists become a larynx. It is a little more difficult to find one's way into the eurythmy, because the movements are not arbitrary, not a combination of momentary gestures, but a taking over of unnoticed movements underlying the sounds in speech and making them visible. - Rudolf Steiner: 21 March 1920, Dornach: Address for doctors, with a performance by children - The pedagogic-hygienic significance of eurythmy

This answer is only a beginning. What does the ear contribute to the work of the larynx? What defines the outer limit of each organ's activity? It is clear that the ear depends on the active receptivity of the larynx, and that we could not hear speech properly without the synchrony of the larynx. See William Condon's research on this phenomenon.
(www.edu-cyberpg.com/Literacy/whatresearchCondon.asp)

What does the instrument of a eurythmist do? It speaks in movement, and in speaking listens. The larynx is metamorphosed outwardly - becoming visible - and the ear is internalised as the eurythmist's kinesthetic experience, and sometimes as entrained somatic sensations in the actively observing spectator.

The larynx is not complete without the capacity of another's ear to sensitively receive its sounding voice. The human ear is not sufficiently able to distinguish the sounds that constitute words of human speech, according to Steiner. He asserts that we need the skill of the Genius of Language, an archangel, to distinguish the sounds of speech. (Wisdom of Man, of the Soul and of the Spirit: Lecture 2.
The full text is online at wn.rsarchive.org/Lectures/WisdoMan/19091025a01.html)

To the question, what is movement, Steiner answered, "If you want to understand movement, study speech". Does Steiner imply that all movement is speech? If that is so, eurythmy can be seen to serve the Genius of Language in making the archangelic movements of language visible for all to see. Can we therefore imagine that in hearing speech, an archangel leans down and reaches into us so that we can hear the phonemes, the characteristic sounds of speech? In eurythmy we imbue the whole body with the movements of archangels. The whole takes up the task of the part. The larynx is revealed as the dancing ground of archangels.

Discover Eurythmy aims to encourage more interest in eurythmy, dialogue between eurythmists and enthusiasts, and also more questions!