Why Goddess Saraswathi Devi sits on the stone ?

If we see in some of the pictures the Goddess Saraswathi devi sits on the stone. 

She holds the Veena with the hands. The name of that Veena is called Mahati. 

There are 

many names for  Goddess Saraswathi. Vani, Geervani, Brahmi, Bharati and

Bhasha etc are synonymous names.

Sarah Prasaranam means Sarvatra Asteeti Saraswathi. She pervades every where.

And also in the Brahmaloka, patronage the Brahma Sarah (lake) and flows in the 

form of 

River as per Amarakosam.

But the Goddess Saraswathi sits on the stone means  that she is stable, not like  the 

Goddess Sri Lakshmi Devi who is unstable and moves from one place to another.

The wealth may be lost but the leaned Vidya (education) and wisdom can not go.

Saraswathi Devi’s carriage is  Divine Swan ( Deva Hamsah). The Hamsa 

means it has a great  Divine knowledge.

It seprates the milk and the mixed water and drinks only the milk but not the water. 

It has such wonderful capacity.

This significe by the knowledge we can achieve any thing  in this world.

Regarding the Peacock, against to the nature, without any copulation , the Peahen 

produce the progeny by drinking the water from the eyes of Peacock.