The origin of human half-life relationship

From the poem "Life".

Half-life is half-life, nine points are sour and one point is sweet.

Drink half an altar of spirits with the wind and leave me a cup for more than a year.

I am a layman, not a fairy, and I will be unlucky after half my life.

The rest of my life is chic, and a cup of green tea is fleeting.