The Yoga Sutras of Patanjali, by Charles Johnston, , at sacred-texts.com
The third book of the Sutras has fairly completed the history of the birth and growth of the spiritual man, and the enumeration of his powers; at least so far as concerns that first epoch in his immortal life, which immediately succeeds, and supersedes, the life of the natural man.
In the fourth book, we are to consider what one might call the mechanism of salvation, the ideally simple working of cosmic law which brings the spiritual man to birth, growth, and fulness of power, and prepares him for the splendid, toilsome further stages of his great journey home.
The Sutras are here brief to obscurity; only a few words, for example, are given to the great triune mystery and illusion of Time; a phrase or two indicates the sweep of some universal law. Yet it is hoped that, by keeping our eyes fixed on the spiritual man, remembering that he is the hero of the story, and that all that is written concerns him and his adventures, we may be able to find our way through this thicket of tangled words, and keep in our hands the clue to the mystery.
The last part of the last book needs little introduction. In a sense, it is the most important part of the whole treatise, since it unmasks the nature of the personality, that psychical 'mind,' which is the wakeful enemy of all who seek to tread the path. Even now, we can hear it whispering the doubt whether that can be a good path, which thus sets 'mind' at defiance.
If this, then, be the most vital and fundamental part of the teaching, should it not stand at the very beginning? It may seem so at first; but had it stood there, we should not have comprehended it. For he who would know the doctrine must lead the life, doing the will of his Father which is in Heaven.