The supreme Shastra of the integral Yoga is the eternal Veda secret in the heart of every thinking and living being....

For the sadhaka of the integral Yoga it is necessary to remember that no written Shastra, however great its authority or however large its spirit, can be more than a partial expression of the eternal Knowledge....

The Synthesis of Yoga, pp.  53–54:

The supreme Shastra of the integral Yoga is the eternal Veda secret in the heart of every thinking and living being. The lotus of the eternal knowledge and the eternal perfection is a bud closed and folded up within us. It opens swiftly or gradually, petal by petal, through successive realisations, once the mind of man begins to turn towards the Eternal, once his heart, no longer compressed and confined by attachment to finite appearances, becomes enamoured, in whatever degree, of the Infinite. All life, all thought, all energising of the faculties, all experiences passive or active, become thenceforward so many shocks which disintegrate the teguments of the soul and remove the obstacles to the inevitable efflorescence. He who chooses the Infinite has been chosen by the Infinite. He has received the divine touch without which there is no awakening, no opening of the spirit; but once it is received, attainment is sure, whether conquered swiftly in the course of one human life or pursued patiently through many stadia of the cycle of existence in the manifested universe.

The Synthesis of Yoga, pp.  55–56:

For the sadhaka of the integral Yoga it is necessary to remember that no written Shastra, however great its authority or however large its spirit, can be more than a partial expression of the eternal Knowledge. He will use, but never bind himself even by the greatest Scripture. Where the Scripture is profound, wide, catholic, it may exercise upon him an influence for the highest good and of incalculable importance. It may be associated in his experience with his awakening to crowning verities and his realisation of the highest experiences. His Yogamay be governed for a long time by one Scripture or by several successively,— if it is in the line of the great Hindu tradition, by the Gita, for example, the Upanishads, the Veda. Or it may be a good part of his development to include in its material a richly varied experience of the truths of many Scriptures and make the future opulent with all that is best in the past. But in the end he must take his station, or better still, if he can, always and from the beginning he must live in his own soul beyond the limitations of the word that he uses. The Gita itself thus declares that the Yogin in his progress must pass beyond the written Truth,— sabdabrahm ativartate — beyond all that he has heard and all that he has yet to hear,— srotavyasya srutasya ca. For he is not the sadhaka of a book or of many books; he is a sadhaka of the Infinite.