by Charles Johnston: The Yoga Sutras of Patanjali are in themselves exceedingly brief, less than ten pages of large type in the original. Yet they contain the essence of practical wisdom, set forth in admirable order and detail. 
The theme, if the present interpreter be right, is the great regeneration, the birth of the spiritual from the psychical man: the same theme which Paul so wisely and eloquently set forth in writing to his disciples in Corinth, the theme of all mystics in all lands.
We think of ourselves as living a purely physical life, in these material bodies of ours. In reality, we have gone far indeed from pure physical life; for ages, our life has been psychical, we have been centred and immersed in the psychic nature. Some of the schools of India say that the psychic nature is, as it were, a looking-glass, wherein are mirrored the things seen by the physical eyes, and heard by the physical ears. But this is a magic mirror; the images remain, and take a certain life of their own. Thus within the psychic realm of our life there grows up an imaged world wherein we dwell; a world of the images of things seen and heard, and therefore a world of memories; a world also of hopes and desires, of fears and regrets. Mental life grows up among these images, built on a measuring and comparing, on the massing of images together into general ideas; on the abstraction of new notions and images from these; till a new world is built up within, full of desires and hates, ambition, envy, longing, speculation, curiosity, self-will, self-interest.
The teaching of the East is, that all these are true powers overlaid by false desires; that though in manifestation psychical, they are in essence spiritual; that the psychical man is the veil and prophecy of the spiritual man.
The purpose of life, therefore, is the realizing of that prophecy; the unveiling of the immortal man; the birth of the spiritual from the psychical, whereby we enter our divine inheritance and come to inhabit Eternity. This is, indeed, salvation, the purpose of all true religion, in all times.
Patanjali has in mind the spiritual man, to be born from the psychical. His purpose is, to set in order the practical means for the unveiling and regeneration, and to indicate the fruit, the glory and the power, of that new birth.
Through the Sutras of the first book, Patanjali is concerned with the first great problem, the emergence of the spiritual man from the veils and meshes of the psychic nature, the moods and vestures of the mental and emotional man. Later will come the consideration of the nature and powers of the spiritual man, once he stands clear of the psychic veils and trammels, and a view of the realms in which these new spiritual powers are to be revealed.
At this point may come a word of explanation. I have been asked why I use the word Sutras, for these rules of Patanjali’s system, when the word Aphorism has been connected with them in our minds for a generation. The reason is this: the name Aphorism suggests, to me at least, a pithy sentence of very general application; a piece of proverbial wisdom that may be quoted in a good many sets of circumstance, and which will almost bear on its face the evidence of its truth. But with a Sutra the case is different. It comes from the same root as the word ‘sew,’ and means, indeed, a thread, suggesting, therefore, a close knit, consecutive chain of argument. Not only has each Sutra a definite place in the system, but further, taken out of this place, it will be almost meaningless, and will by no means be self-evident. So I have thought best to adhere to the original word. The Sutras of Patanjali are as closely knit together, as dependent on each other, as the propositions of Euclid, and can no more be taken out of their proper setting.
In the second part of the first book, the problem of the emergence of the spiritual man is further dealt with. We are led to the consideration of the barriers to his emergence, of the overcoming of the barriers, and of certain steps and stages in the ascent from the ordinary consciousness of practical life, to the finer, deeper, radiant consciousness of the spiritual man.
