The Tamil Siddhas did not define the silence as a speechless state but as a state of mystic silence where the self is emptied of its contents; it is a state where ego, mind and thinking disappear. The term vettaveli is an expression of mystic experience that leads gradually to convey the meaning of silence. Silence is a mystic metaphor employed by the Siddhas for distinctionlessness. It is a state of non-duality; it is a state of total disappearance of all distinctions, where we stop making use of the reason-mind whose function is to distinguish and define.
The state of silence is a state of consent, of being one with the Reality. The “silence” of the Siddhas refers to an indescribable level of the Reality –the non-verbal, non-symbolic and absolutely indefinable. It is an imageless knowledge. The Siddhas express the state of silence as a state of “beyond the beyond”. This expression means that the Ultimate Reality is beyond the three thresholds of man –the threshold of world, the threshold of time and the threshold of his limiting consciousness.
The silence retreats are thus considered as a space to try and experience this mystic silence which the Siddhas speak of. They are based on the techniques used by the Siddhas, taking as a starting point the pranayama and the mantra so that we can access this space of Pure Consciousness. As Siddha Konganar says, the silence is the real Yoga.
You can find below the words of a Siddha with relation to silence:
As you gather silence, go deeper in silence.
Silence becomes the immense totality.
As one goes deeper in silence, digs deeper in it,
Faultless silence appears by itself.
Going further into meditative silence
The pathway of knowledge-realization is seen.
The steps that form the entrance to silence
Begin with the silence when the lips are closed
Siddha Konganar, The Yoga of the 18 Siddhas an Anthology. Editor: T.N Ganapathy.