Everything is Siva

*Abhinavagupta's Paramarthasara * 

The enlightened being's meditation is without cessation because the Lord creates diverse forms and his meditations constitute the variety of forms depicted by the mind.

Yogaraja's commentary:

A form which has been imagined is destroyed when the attention of the mind is diverted and goes elsewhere. But meditation by an enlightened spiritual adept is uninterrupted because the Lord, infinite Siva, who is the same as the pure Self of the spiritual adept, incessantly creates the variety of forms by operating his power of action (kriya). He possesses infinite powers for imagining any form he likes. The continuous creation of the infinite variety of objects takes the form of his conceptualizations or imaginings, which he depicts in the mirror of his mind. His imaginings are without beginning or end, and they are nothing but his meditation. For one who knows all this, all the activities of his mind, free from limitations, become divine.

When a particular deity is meditated upon, then the meditation takes a definite form in accordance with the imagination of the face and limbs etc. But in fact every activity of the mind is only a manifestation of the highest sakti. Thus, whatever form is imagined in the meditation of the spiritual adept as a mental formulation is not different from illumination, despite its being only the mind's imaginings. This is due to the omnipresence of pure consciousness. This has been stated in the Svacchanda Tantra:

'Wherever the mind goes, one should concentrate one's mind there. Where can it go that is not Siva, as everything is Siva.'

Similarly the Saiva Upanishad says:

'O dear one, wherever the mind goes, externally or not, it is not separate from Siva, who pervades everywhere.'