Themes
We live as we dream: alone.
— Joseph Conrad · Heart of Darkness

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker sees human life as fundamentally solitary, likening waking existence to dreaming, where no one else can enter our experience. However close people seem, each of us inhabits an inner world alone. The colon stresses the point: isolation is presented as the shared, resigned condition of living.
Context reviewed