In plain words
The knowledge recognised through inquiry into things is knowledge of substances. Is it the knowledge that takes a sense object as its basis and recognises what is special in it? That too is only knowledge of objects. By knowledge that has been acquired, no one at all can recognise the divine Ātma-principle. To cut a diamond, you need a diamond. To take out a thorn that has broken off in your foot, you need a thorn itself. To recognise the Ātma-principle, you need Ātma-jñāna itself.
Whatever we today regard as Jñāna in the physical world, all of it is only Ajñāna. Ātma-jñāna alone is true Jñāna. Say Ātma or say Jñāna: the two are one. True awareness itself is Jñāna. The knowledge we come to by gathering substances together, collecting objects and so learning, is merely equal to Ajñāna. This Jñāna has no triad of jñāna, jñeya and jñātā. Jñāna, jñeya and jñātā are vṛttis that belong to the Manas. The principle that is the root foundation, once the Manas is destroyed: that alone is this Jñāna. These powers of inquiry that belong to the Manas all go along with delusion. It rests on the vṛtti. What man has seen, what man has heard, what man experiences, what man practises: all these are merely delusions that go with the body taken for the self. The svabhāva of this Manas is simply the principle of the body itself. The Manas cannot stay even a single moment without some form, some object, some thing. The Manas leans on the body for its support. The eyes, nose, ears and mouth that this body has, these five elements, all of them: through these alone the Manas experiences everything. The Manas sees through the eyes of the body. The Manas hears through the ear of the body. The Manas has no form. The Manas itself is Māyā. The Manas itself is desire. The Manas itself is Prakṛti. The Manas itself is Avidyā. The Manas itself is the delusion born of Prakṛti. Through a Manas joined to such delusion, it is very hard for us to understand the Brahman-principle, which is Satya and eternal. What, for us, is true Jñāna? Jñāna means this: when the Manas has brought the senses under control and destroyed the senses, the Manas too vanishes. At that time the principle of silence, which is Praśānti, takes shape. The silence that comes of this destruction of the Manas is true Jñāna. This Jñāna is not gained through cleverness, nor through skill of the Buddhi, nor through any other kind of ideal.