राजविद्या राजगुह्यं पवित्रमिदमुत्तमम् ।प्रत्यक्षावगमं धर्म्यं सुसुखं कर्तुमव्ययम् ॥
rājavidyā rājaguhyaṁ pavitramidamuttamampratyakṣāvagamaṁ dharmyaṁ susukhaṁ kartumavyayam
This is the king-knowledge, the king-secret (the wisdom of all wisdoms, the secret of all secrets), it is a pure and supreme light which one can verify by direct spiritual experience, it is the right and just knowledge, the very law of being. It is easy to practise and imperishable.
Compiled rendering · Anilbaran Roy
Essays on the Gita
This truth is the secret of being which the Gita is now going to apply in its amplitude of result for our inner life and our outer works. What it is going to say is the most secret thing of all.* It is the knowledge of the whole Godhead, samagraṁ mām, which the Master of his being has promised to Arjuna, that essential knowledge attended with the complete knowledge of it in all its principles which will leave nothing yet to be known. The whole knot of the ignorance which has bewildered his human mind and has made his will recoil from his divinely appointed work, will have been cut entirely asunder. This is the wisdom of all wisdoms, the secret of all secrets, the king-knowledge, the king-secret. It is a pure and supreme light which one can verify by direct spiritual experience and see in oneself as the truth: it is the right and just knowledge, the very law of being. It is easy to practise when one gets hold of it, sees it, tries faithfully to live in it.
The Arya — text not in the CWSA
Gita IX. 1–3