In Tamil the consonants and vowels are known as ‘body-letters’ (mey-ezhuttu) and ‘life-letters’ (uyir-ezhuttu) respectively . So in the praNava of Shiva-Shakti, the Lord corresponds to the ‘body-letter’ and the Goddess corresponds to the ‘life-letter’. And this coordinates with the thought that Shiva is the body and Shakti is the soul.
Secondly, in Tamil parlance it is common to say: ‘If you have the power (Shakti) to do this, do it; otherwise stay quiet as ‘shiva’ (‘shivane-enRu iru’)! This again coordinates with the thought that Shiva is the actionless substratum and Shakti is the switch that switches everything into action!