《汉书·志·沟洫志》
不加以修治的话，北面决口就使四五郡受害，南面决口就会使十多郡受害，到这之后再来忧虑它。就已晚了。 
不豫修治，北决病四五郡，南决病十余郡，然后忧之，晚矣。 
If it is not repaired, a break in the north will affect four or five commanderies, and a break in the south will affect ten or more commanderies. It will be too late to worry about it after that happens.