Now we have said before, that each unit of change or evolution is measured by this unit of time _kshaṇa_ or moment; or rather the units of change are expressed in terms of these moments or _kshaṇas_. Of course in our ordinary consciousness these moments of change cannot be grasped, but they can be reasonably inferred. For at the end of a certain period we observe a change in a thing; now this change, though it becomes appreciable to us after a long while, was still going on every moment, so, in this way, the succession of evolution or change cannot be distinguished from the moments coming one after another. Thus the _Yoga-sūtra_ says in IV. 33: “Succession involving a course of changes is associated with the moments.” Succession as change of moments is grasped only by a course of changes. A cloth which has not passed through a course of changes through a series of moments cannot be found old all at once at any time. Even a new cloth kept with good care becomes old after a time. This is what is called the termination of a course of changes and by it the succession of a course of changes can be grasped. Even before a thing is old there can be inferred a sequence of the subtlest, subtler, subtle, grossest, grosser and gross changes (_Tattvavaiśāradī_, IV. 33).[25] Now as we have seen that the unit of time is indistinguishable from the unit of change or evolution, and as these moments are not co-existing but one follows the other, we see that there is no past or future existing as a continuous before or past, and after or future. It is the present that really exists as the manifested moment; the past has been conserved as sublatent and the future as the latent. So the past and future exist in the present, the former as one which has already had its manifestation and is thus conserved in the fact of the manifestation of the present. For the manifestation of the present as such could not have taken place until the past had already been manifested; so the manifestation of the present is a concrete product involving within itself the manifestation of the past; in a similar way it may be said that the manifestation of the present contains within itself the seed or the unmanifested state of the future, for if this had not been the case, the future never could have happened. So we see that the whole world undergoes a change at one unit point of time, and not only that but it conserves within itself all the past and future history of cosmic evolution.