Agathiyar in speaking about our composition as a whole talks about the physical body or Udal which is a vehicle for the breath or Uyir and soul or Atma to travel within. The physical body is assembled by taking the 5 tattvas from each parent in a unique proportion. Science tells us that the embryo begins to feed on womb-milk secretions and after 11 weeks the mother’s blood supply is delivered via the umbilical cord to the fetus. What a marvel. We learn that fetal breathing is detectable as early as 10 weeks of gestation in the human fetus. The time the soul makes its entry is very subjective and varies among scholars, sacred texts, and science. We are said to be alive only if all three are intact and in the body. If any one component leaves the team death occurs.
The Atma or soul is pure to its essence. It is one with the Param. But like all things it gets tainted too. It is the Tattvas that give form to it. With the first inhalation Life or Uyir comes within the Body or Pindam, giving it a voice. It tends to veil it further. Now known as the Jeevatma (Jeeva Atma) or Spirit it believes it is a separate entity from the Param. It sees itself as separate from its bigger Self. The purpose of man is to know Himself. This would be attaining Mukti. Bringing oneself to spiritual practices, the Tava Kanal or as Agathiyar says, "The radiant heat [tejas tapah] of these spiritual experiences, also greatly expand the holding sack of causal body [karanam sharira], making it possible for a quick release [mukti] of the bound soul [bandhit atama]." Attaining this knowledge of the Self while living he walks the ground as a Jeevan Mukta. He is given the freedom to shed or leave the mortal frame as and when he wishes.
We learn from Ruzbeh N Bharucha's writings at https://www.speakingtree.in/allslides/the-three-bodies-that-encase-the-soul-633928 of the three bodies and its nature. What is very obvious to us is our physical body made of matter, of the five elements namely Ether, Air, Fire, Water, and Earth.
Next, we are told of the astral body, made of the subte three elements namely mind or manas, subconscious or Chitta, and the organs of knowledge or Jnana Indriyas: the eyes, ears, nose, tongue, and skin. This implies the importance of these senses to be diverted towards a superior agenda where we then arrive at Jnana or Divine Wisdom. Of late Agathiyar has been asking us to go within. Many saints and sages are seen to remain still.
Speaking on the various bodies, Ruzbeh Bharucha writes that the causal body, made of three elements, covers both the subtle or astral body and our physical body. And the three elements are 1.Param Akash Tatwa or Prime Ether, 2.Param Vayu Tatwa or Prime Air and 3.Param Agni Tatwa or Prime Fire. He writes that the Param Vayu Tatva and Param Agni Tatva that arouses desires and intentions, gets us entangled more and more with the body and its relationship, thus having our causal body react to these.
Ruzbeh mentions seven cosmic energies residing in the causal body that is continuously charged by the cosmic energies in the atmosphere. In sitting still do we then tap into them enhancing the inherent energies?
Since sitting in silence has the tendency to bring one to be filled with more Param Akash Tatva we have all the more reason then to sit in silence.
For one seeking and working towards his goals of attaining the Divine state, there is a more urgent need to focus on silence because Vairagya Vruti, or disenchantment sets in as we delve deeper and deeper into a state of silence says Ruzbeh. Hence the reason why Lord Muruga asked Arunagiri to remain still and the reason Agathiyar asked us to go within dawns now.
Soon having been accustomed daily to the place and mood created, the self settles on its own nudging wonderfully into its domain - that of silence. In these hours of silence, the "self" speaks with the "higher self" whom we have given numerous names and forms. All queries are answered in silence. This is the Mouna Guru teaching us in silence.