lost in the "they", can dwell in tranquillized familiarity. When in falling we flee into the "at-home" of publicness, we flee in the face of the "not-at-home"; that is, we flee in the face of the uncanniness which lies in Dasein —in Dasein as thrown Being-in-the-world, which has been delivered over to itself in its Being. This uncanniness pursues Dasein constantly, and is a threat to its everyday lostness in the "they", though not explicitly. This threat can go together factically with complete assurance and self-sufficiency in one's everyday concern. Anxiety can arise in the most innocuous Situations. Nor does it have any need for darkness, in which it is commonly easier for one to feel uncanny. In the dark there is emphatically 'nothing' to see, though the very world itself is still 'there', and 'there' more obtrusively.
If we Interpret Dasein's uncanniness from an existential-ontological point of view as a threat which reaches Dasein itself and which comes from Dasein itself, we are not contending that in factical anxiety too it has always been understood in this sense. When Dasein "understands" uncanniness in the everyday manner, it does so by turning away from it in falling; in this turning-away, the "not-at-home" gets 'dimmed down'. Yet the everydayness of this fleeing shows phenomenally that anxiety, as a basic state-of-mind, belongs to Dasein's essential state of Being-in-the-world, which, as one that is existential, is never present-at-hand but is itself always in a mode of factical Being-there1—that is, in the mode of a state-of-mind. That kind of Being-in-the-world which is tranquillized and familiar is a mode of Dasein's uncanniness, not the reverse. From an existential-ontological point of view, the "not-at-home" must be conceived as the more primordial phenomenon .
And only because anxiety is always latent in Being-in-the-world, can such Being-in-the-world, as Being which is alongside the 'world' and which is concernful in its state-of-mind, ever be afraid. Fear is anxiety, fallen into the 'world', inauthentic, and, as such, hidden from itself. 
After all, the mood of uncanniness remains, factically, something for which we mostly have no existentiell understanding. Moreover, under the ascendancy of falling and publicness, 'real' anxiety is rare. Anxiety is often conditioned by 'physiological' factors. This fact, in its facticity, is a problem ontologically, not merely with regard to its ontical causation and course of development. Only because Dasein is anxious in the very depths of its Being, does it become possible for anxiety to be elicited physiologically.
Even rarer than the existentiell Fact of "real" anxiety are attempts to
1 Here we follow the earlier editions in reading 'Da-seins'. In the later editions the hyphen appears ambiguously at the end of a line.