Jetzt ist der Hinweis angebracht, dass wir überhaupt gerne 'dual' denken,
left
-
right
clear
-
dark
up
-
down
friend
-
fiend
good
-
evil
God
-
Devil
are such couples of terms, expandable as you like. Tertium non datur, there is no third between, The middle becomes a borderline between two alternatives. There is no need to think that way in life but in this place this schematic pattern is to be cultivated, we will use it.