Samādhi we have seen is the mind’s becoming one with an object by a process of acute concentration upon it and a continuous repetition of it with the exclusion of all other thoughts of all kinds. We have indeed described the principal stages of the advancement of samprajñāta Yoga, but it is impossible to give an exact picture of it with the symbolical expressions of our concepts; for the stages only become clear to the mental vision of the Yogin as he gradually acquires firmness in his practice. The Yogin who is practising at once comes to know them as the higher stages gradually dawn in his mind and he distinguishes them from each other; it is thus a matter of personal experience, so that no teacher can tell him whether a certain stage which follows is higher or lower, for Yoga itself is its own teacher. Even when the mind is in the samprajñāta state it is said to be in vyutthāna (phenomenal) in comparison with the nirodha state, just as the ordinary conscious states are called vyutthāna in comparison with the samprajñāta state; the potencies of the samprajñāta state become weaker and weaker, while the potencies of the nirodha state become stronger and stronger until finally the mind comes to the nirodha state and becomes stable therein; of course this contains within itself a long mental history, for the potency of the nirodha state can become stronger only when the mind practises it and remains in this suppressed condition for long intervals of time. This shows that the mind, being made up of the three guṇas, is always suffering transformations and changes. Thus from the ordinary state of phenomenal consciousness it gradually becomes one-pointed and then gradually becomes transformed into the state of an object (internal or external), when it is said to be undergoing the samādhi pariṇāma or samādhi change of the samprajñāta type; next comes the change, when the mind passes from the samprajñāta stage to the state of suppression (_nirodha_). Here also, therefore, we see that the same dharma, lakshṇa, avasthāpariṇāma which we have already described at some length with regard to sensible objects apply also to the mental states. Thus the change from the vyutthāna (ordinary experience) to the nirodha state is the dharmapariṇāma, the change as manifested in time, so that we can say that the change of vyutthāna into nirodha has not yet come, or has just come, or that the vyutthāna state (ordinary experience) exists no longer, the mind having transformed itself into the nirodha state. There is also here the third change of condition, when we see that the potencies of the samprajñāta state become weaker and weaker, while that of the nirodha state becomes stronger and stronger. These are the three kinds of change which the mind undergoes called the dharma, lakshaṇa and avasthā change. But there is one difference between this change thus described from the changes observed in sensible objects that