The weakness of the play, as I have said, lies in its duality of action.

Duality is the root, out of which alone, for mortals, happiness can spring.

This then is the duality of my day and my night being: a duality so bitter to an adolescent.

In her, the duality of her being had created two distinct lives.

In a way, every one must have a sort of duality—a good and evil principle.

But this duality of intuition Kant neither would nor could admit.

At these moments the soul seems to rend and tear at the very roots of this duality.

Their duality is unfathomable because the soul is unfathomable.

Without such a duality it is impossible to conceive any soul existing.

The following are a few examples of duality taken from nature.