As particular case of the previous thing, the existence of self is a certain subjective fact, of which there is no doubt. But its conceptualization as something external or by means of its relation with the rest of objects of the Universe produces a description of self that because objective is susceptible of error. That is, when one is observed itself, not when one establishes and puts test objective hypotheses about the nature of self as if it was an external object, but, simply, when one is observing itself, obtains a certainty of its observation.
But the subjective certainty difficultly can be explained with words. It does not make reference to the nature of concepts, or its relation to each other. What we obtain by means of the subjective experience is a existencial certainty, that it seems that only can be expressed in poetic forms, combinning words like: "God", "I", "Universe", "Everything", "Absolute", etc.
Without on approval clearing importance to the scientific method based on the creation and putting of objective hypotheses, probably indispensable for the survival --of self--, in this text stands out the habitual lack of conscience of the existence of the own subjective experience itself, probably also indispensable for the survival --of the essence of self- -.