That alone is called ultimate truth, which is a fact that can never be changed under any circumstances. One must make an effort to know the ultimate truth. Soul is there always in the form of consciousness. Everyone has got it, there is nothing new to be acquired; only they have to be sharp enough to grasp and understand and assimilate it, when told about it. But there is a difference between understanding and realization. Effort is required for this understanding only, whereas once understood no special effort is needed to remember his understanding: until then he only has an idea of soul, he only partially understand it. But once he thoroughly grasps what it is and that all these things are soul, he will then constantly find it present everywhere without further effort, because he will perceive ultimate truth by understanding, even in the midst of worldly existence.
When there is only one thing that is soul, then there is nothing to change, nothing to appear or disappear; when one speaks of remembering or forgetting soul that implies he believe in the existence of something else, i.e. a second thing, which is to be remembered. That would show he has not known that all is one. But knowing it, there is no second, consequently no intermittent perception of soul, but a permanent effortless understanding and assimilation that it alone is.
When one gets a glimpse of truth he has to try to repeat it a number of times in order to establish it. The soul /self must raise itself by the soul/ self.
The difference between a physical truth and a spiritual truth, the former can evolve or change; the latter is ultimate and final.
