Emptiness

The only worthwhile portion of anything
Is its emptiness.

For example -

The emptiness of a bottle, glass, bucket, room etc.
The emptiness is what makes all objects valuable.

Same with ourselves -

If we enter the tavern of the cupbearer
With a full cup
Then He will not be able to fill it
With His ravishing, sparkling wine
Of love and bliss.

For -

The cup of our life
Must always be empty
When entering the
Cupbearers tavern.