Husserl speaks of ruckfrage

Husserl speaks of

going “back” [ruckfrage]

because we must begin where we are;

and where we are includes a sense of self whose identity is temporarily seated in the sedimented layers of consciousness built up through our temporal experiences.

Hence, if we are to encounter the “I” we must dig back down through those layers or we must continually present ourselves with the question:

who is “I”?

as we consider the great variety of things with which we have identified.

This questioning back is the method of the phenomenological reduction and aims to lay bare the “I”—the condition for the possibility of knowledge.