What does it mean to wish the mysterious bird pure?

I hope there will be a good harvest in the coming year, which will increase at the beginning of the year.

The poem "The mysterious bird is spring, and the black dragon is old" comes from Old Tang Book Le San: "The mysterious bird is spring, and the black dragon is old." .

This ancient prose expresses his expectation for a bumper harvest, as well as his ambition for promotion.