205. Sarvayantrātmikā
Devi represents all the yantras corresponding to all the sound forms of the mantras.
Yantra means an engine, a vehicle, a seat or a place for an upādhi, where a conscious force can be centered. Śrī Yantra is an upādhi for Śrī Devi to manifest. Durgā yantra is a vehicle for Goddess Durgā and so on. Devi represents all such yantras.
From the definition of a Yantra, it is clear that it is an upādhi. An upādhi is a vehicle of consciousness. Our bodies and minds are vehicles of consciousness. Hence, they are also upādhi, yantras. Devi has for Her body all bodies. She resides in all of us.
In the phalaśruti of Lalitā Triśati, it is written that “śrī cakram śivayo babhuḥ”. The Śrī Cakra is the vehicle, the upādhi formed by the Śiva and Śakti in union, i.e. that such a state of union is the worship of Śrī Lalitā. The Śrī Yantra is formed by four upward triangles and five downward triangles interpenetrating each other. The four upward triangles are the Śivas and the five downward triangles are the Śakti.
The four Śiva Tattvas are Sarveśvara, Sadāśiva, Sarvavyāpaka and Sarvajña meaning controlling all, always present, present at all places and knowing all.
The five Śakti tattvas are grace, projection, creation, maintenance and destruction.
Śrī Cakra represents the union of these five dynamic forces with the four static observers.
Recognition that the body of a devotee is itself an excellent Śrī Cakra has led to the worship of the body in the form of Suvāsinī pūjā and Kumārī pūjā.
Suvāsinī pūjā means worshipping a married woman as a representation, a yantra of the deity.
Worship of the virgin girls is known a Kumārī pūjā.
Both these forms of worship are external modes of worship called Bahya pūjā. Even the worship of a mental Śrī Yantra, an abstract symbol of the union of Śiva and Śakti comes under the category of Bahya pūjā.
Source: Śrī Amṛtānandanātha Sarasvatī "Sudhā Syandinī Bhāṣyaṃ" Typed Manuscript
(an incomplete commentary on Lalitā Sahasranāma)