There are a few words, constantly recurring, which need brief definitions, in order to avoid confusion; they are: Unfolding, Evolution, Spirituality, Psychism, Yoga and Mysticism.
"Unfolding" always refers to consciousness, "evolution" to forms. Evolution is the homogeneous becoming the heterogeneous, the simple becoming complex. But there is no growth and no perfectioning for Spirit, for consciousness; it is all there and always, and all that can happen to it is to turn itself outwards instead of remaining turned inwards. The God in you cannot evolve, but He may show forth His powers through matter that He has appropriated for the purpose, and the matter evolves to serve Him. He Himself only manifests what He is. And on that, many a saying of the great mystics may come to your mind: "Become," says St. Ambrose, "what you are"--a paradoxical phrase; but one that sums up a great truth: become in outer manifestation that which you are in inner reality. That is the object of the whole process of Yoga.
"Spirituality" is the realisation of the One. "Psychism" is the manifestation of intelligence through any material vehicle.[FN#5: See London Lectures of 1907, "Spirituality and Psychism".]
"Yoga" is the seeking of union by the intellect, a science; "Mysticism" is the seeking of the same union by emotion.[FN#6: The word yoga may, of course, be rightly used of all union with the self, whatever the road taken. I am using it here in the narrower sense, as peculiarly connected with the intelligence, as a Science, herein following Patanjali.]
See the mystic. He fixes his mind on the object of devotion; he loses self-consciousness, and passes into a rapture of love and adoration, leaving all external ideas, wrapped in the object of his love, and a great surge of emotion sweeps him up to God. He does not know how he has reached that lofty state. He is conscious only of God and his love for Him. Here is the rapture of the mystic, the triumph of the saint.
The yogi does not work like that. Step after step, he realises what he is doing. He works by science and not by emotion, so that any who do not care for science, finding it dull and dry, are not at present unfolding that part of their nature which will find its best help in the practice of Yoga. The yogi may use devotion as a means. This comes out very plainly in Patanjali. He has given many means whereby Yoga may be followed, and curiously, "devotion to Isvara'' is one of several means. There comes out the spirit of the scientific thinker. Devotion to Isvara is not for him an end in itself, but means to an end the concentration of the mind. You see there at once the difference of spirit. Devotion to Isvara is the path of the mystic. He attains communion by that. Devotion to Isvara as a means of concentrating the mind is the scientific way in which the yogi regards devotion. No number of words would have brought out the difference of spirit between Yoga and Mysticism as well as this. The one looks upon devotion to Isvara as a way of reaching the Beloved; the other looks upon it as a means of reaching concentration. To the mystic, God, in Himself is the object of search, delight in Him is the reason for approaching Him, union with Him in consciousness is his goal; but to the yogi, fixing the attention on God is merely an effective way of concentrating the mind. In the one, devotion is used to obtain an end; in the other, God is seen as the end and is reached directly by rapture.