Portal

"The mirror is, after all, a utopia, since
it is a placeless place. In the mirror, I see myself there where I am not, in an unreal,
virtual space that opens up behind the surface; I am over there, there where I am not,
a sort of shadow that gives my own visibility to myself, that enables me to see myself
there where I am absent: such is the utopia of the mirror. . . .

But it is also a heterotopia in so far as
the mirror does exist in reality, where it exerts a sort of counteraction on the position
that I occupy. From the standpoint of the mirror I discover my absence from where I am
since I see myself over there. Starting from this gaze that is, as it were, directed toward me,
from the ground of this virtual space that is on the other side of the glass, I come back
toward myself I begin again to direct my eyes toward myself and to reconstitute myself
there where I am. The mirror functions as a heterotopia in this respect: it makes this place
that I occupy at the moment when I look at myself in the glass at once absolutely real,
connected with all the space that surrounds it, and absolutely unreal, since in order
to be perceived it has to pass through this virtual point which is over there."

― Michel Foucault, from "Of Other Spaces"