In the bible an unclean spirit gets driven out of a man and goes throw dry places seeking rest and does not find it and then it says it will return to the house it left.
When it returns it finds the house swept clean and put in order and it brings in seven spirits more wicked then itself to live there with him and the final condition of that man is worse than the first.
This is how it will be with the wicked and adulterous generation.
SO WHAT DOES IT MEAN?
Dryness is a symbol for fulfillment without satisfaction meaning the unclean spirit was not housed in a room of love
The other thing is some of the evil was driven out of the man but there was a part of the evil that remained
COMBINED TOGETHER IT MEANS
They drove out some of the evil that was in their hearts but once the evil was driven out they failed to replace the left over space with Good
Since they failed to cover the empty places in their soul with good after the evil was driven out in a partial way
The evil that remained festered and became even more evil because there was no Good to prevent the weeds from overtaking the garden and the evil was more angry than it was before
Like cancer that returns resistant to treatment and more aggressive because it wasn't fully removed the first time
When evil is driven out good must come in to take its place because order without love is worse than disorder with love
That is what it means