Back to the old days
To return to the old is an idiom, which means to restore the old, just as it was at the beginning. From the text of the contract.
interpretation
To restore, as if. Restore the old, just like it used to be.
source
The third part of the contract written by Wu Mingshi in Yuan Dynasty: "when Badi came to zuguan village, I only recognized my aunt and uncle, and then I happily went back to the old days."
usage
To return to the original.
Back to the old days
a lamb going astray at a fork in the road - qí lù wáng yáng
destroy evils before they become apparent - dù xī fāng wēi