¶ 54. The Problem of How an Authentic Existentiell Possibility is Attested.
WHAT we are seeking is an authentic potentiality-for-Being of Dasein, which will be attested in its existentiell possibility by Dasein itself. But this very attestation must first be such that we can find it. If in this attestation, Dasein itself, as something for which authentic existence is possible, is to be 'given' to Dasein 'to understand', 1 this attestation will have its roots in Dasein's Being. So in exhibiting it phenomenologically, we include a demonstration that in Dasein's state of Being it has its source.
In this attestation an authentic potentiality-for-Being-one's-Self is to be given us to understand. The question of the "who" of Dasein has been answered with the expression 'Self' .1 Dasein's Selfhood has been defined formally as a way of existing, and therefore not as an entity present-at-hand. For the most part I myself am not the "who" of Dasein ; the they-self is its "who". Authentic Being-one's-Self takes the definite form of an existentiell modification of the "they"; and this modification must be defined existentially.ii What does this modification imply, and what are the ontological conditions for its possibility?
 With Dasein's lostness in the "they", that factical potentiality-for- Being which is closest to it (the tasks, rules, and standards, the urgency and extent, of concernful and solicitous Being-in-the-world) has already been decided upon. The "they" has always kept Dasein from taking hold of these possibilities of Being. The "they" even hides the manner in which it has tacitly relieved Dasein of the burden of explicitly choosing these possibilities. It remains indefinite who has 'really' done the choosing. So Dasein make no choices, gets carried along by the nobody, and thus ensnares itself in inauthenticity. This process can be reversed only if Dasein specifically brings itself back to itself from its lostness in the "they". But this bringing-back must have that kind of Being by the neglect of which
1 '. . . wenn sie dem Dasein es selbst in seiner moglichen eigentlichen Existem; "l!:U verstehen geben" . . .'