A quote from The Prince by Niccolò Machiavelli:

The Romans on this occasion did what should be done

by every wise prince, whose duty it is not only to

provide a remedy for present evils, but at the same time

to anticipate such as are likely to happen. If foreseen

at a distance, they are easily remedied; but if we wait

till they have surrounded us, the opportunity is past and

the malady has become incurable. It happens then as

it happens to physicians in the cure of a consumption,

which in the beginning is easy to cure and difficult to

understand; but when it has neither been discovered

in due time, nor treated upon a proper principle, it

becomes easy to understand and difficult to cure.

The same thing happens in state affairs; by foreseeing

them at a distance, which is done only by men of

talents, the evils that might arise from them are soon

cured; but when from want of foresight they are

suffered to increase to such a height that they are

perceptible to every one, there is no longer any remedy.