Jñānādhiṣṭhānaṁ mātṛkā (ज्ञानाधिष्ठानं मातृका) (sūtrā 4)
Jñāna means knowledge discussed in sūtrā 2, the limited knowledge, adhiṣṭhānaṁ means resting upon and mātṛkā means the Supreme Mother (Lalithā Sahasranāmam nāmā 577 mātṛka varṇa rūpinī. A brief interpretation of this nāmā: She is in the form of 51 alphabets of Sanskrit called mātṛka. These fifty one alphabets are split into six groups and worshipped in the six chakras from mūlādhārā to ājñā. These alphabets have different colors and is said to be closely related to cosmological studies. A comparative narration is drawn between Shiva and Śaktī and vowels and consonants. Vowels are always active and dynamic in nature and therefore vowels are compared to Śaktī; consonants are compared to Shiva. Without Shiva-Shakthi combine, the universe cannot exist, as they are two different aspects of the Brahman. In the same way, sound cannot exist without vowels-consonants combine. The sound originates from Śabda Brahman, whereas the universe originates from the Brahman. She is the Śabda Brahman.) In view of this interpretation, mātṛkā also means letters.
This aphorism means that Śaktī in the form of Śabda Brahman is the source for limited knowledge, the cause of limitation being the three malas, (ānava mala, māyīya mala, and kārma mala) discussed in the third aphorism.
To understand this sūtrā better, understanding Mātṛkā is essential. Mātṛkā can be split into mātṛ + ka. Mātṛ means mother and ka means un-comprehended (ka also means the Brahman). Mātṛkā means that the Divine mother, who is not fully comprehended. She is not fully comprehended because of the malas referred above. Shiva is the Brahman and only Śaktī can lead one to Shiva to attain the final liberation. It becomes essential that Śaktī should be first understood to attain liberation. Lalithā Sahasranāmam nāmā 727 śiva jnāna pradāyinī says, that Śaktī alone can lead to knowledge about Shiva for final liberation. Shiva is static and witnessing as opposed to the kinetic nature of Śaktī, who is the universal dynamic energy. Mostly She is not comprehended properly due to the illusionary effect of māyā. As Mātṛkā, She controls both vācakā and vācyā. Vācakā refers to the letters and vācyā refers to the objects referred by vācakā. For example ‘a door’ comprising of alphabets to form the world table, is vācakā and the same table as an object is known as vācyā. The cause of vācyā is vācakā. Since She originates sound, or becomes the cause of the sound, She is called Śabda Brahman. She is the source of alphabets and their sound (pronounciation) through which objects are known. Hence Śaktī is called as the Creator of the universe. While creating the objective world, She also created illusionary world (māyā), causing deception making Her unaffordable to be comprehend fully. This leads to ignorance as discussed in sūtrā 2.
Because of this innate ignorance, one develops the ability of differentiation to draw comparisons. When the Brahman is omnipresent, all the objects that exist in this universe are merely His reflections. But due to the inborn ignorance, one notices different shapes and forms by different names. Again, the cause of this ignorance is only Śaktī, who casts Her veil of māyā, by sitting on brahmanrandhra (the orifice at the top of the head, through which individual consciousness and cosmic consciousness are interconnected). She is addressed here as citi Mātṛkā. (citi means the power of consciousness that brings about world process. Citi is different from cit, which is the foundational consciousness or the Brahman, discussed in the first sūtrā.). By sitting there, She allows the sensory organs and the components of anthakkaranam (mind, intellect and ego) to play around with the nescient being. They make the nescient being to get involved in worldly matters and bound him with bondage, desire and all that, which are the impediments to realizing the Self. The situation can be visualized as if a terrible form is sitting on a throne, ordering to create mayhem (bondage, desire, etc) in his domain (mind). She is now known as Pīṭheśvarī, whose form is dreadful as She orders mayhem through four of Her primary śaktīs, Ambā, Jeṣṭhā, Raudrī and Vāmā. These four become powerful at different times. If Ambā is powerful one’s fall is imminent. If Jeṣṭhā is powerful, she leads to liberation. Raudrī makes a person confused and also destroys the evil doers. Vāmā is the cause for fruits of world process. These four śaktīs bound a soul with saṃsārā thereby making him to look externally through his sensory organs and preclude him to look within to attain the final liberation. This the effect of malas discussed in earlier sūtrā.
Spanda Kārikā (III.13) says that an individual succumbs to to the powers of these śaktīs. Again, (III.15) says, that these śaktīs are ever ready to conceal the real nature of the soul.