I am firmly convinced, ...

I am firmly convinced, therefore, that to set up a republic which is to last a long time, the way to set about it is to constitute it as Sparta and Venice were constituted; to place it in a strong position, and so to fortify it that no one will dream of taking it by a sudden assault; and, on the other hand, not to make it so large as to appear formidable to its neighbors. It should in this way be able to enjoy its form of government for a long time. For war is made on a commonwealth for two reasons: to subjugate it, and for fear of being subjugated by it.
I am firmly convinced, therefore, that to set up a republic which is to last a long time, the way to set about it is to constitute it as Sparta and Venice were constituted; to place it in a strong position, and so to fortify it that no one will dream of taking it by a sudden assault; and, on the other hand, not to make it so large as to appear formidable to its neighbors. It should in this way be able to enjoy its form of government for a long time. For war is made on a commonwealth for two reasons: to subjugate it, and for fear of being subjugated by it.

Quotes from the same author

No enterprise is more likely to succeed than one concealed from the enemy until it is ripe for execution.
Men in general judge more from appearances than from reality. All men have eyes, but few have the gift of penetration.
Men are less hesitant about harming someone who makes himself loved than one who makes himself feared because love is held together by a chain of obligation which, since men are wretched creatures, is broken on every occasion in which their own interests are concerned; but fear is sustained by dread of punishment which will never abandon you.
Many have imagined republics and principalities which have never been seen or known to exist in reality; for how we live is so far removed from how we ought to live, that he who abandons what is done for what ought to be done, will rather bring about his own ruin than his preservation.
A wise prince then...should never be idle in times of peace but should industriously lay up stores of which to avail himself in times of adversity so that when fortune abandons him he may be prepared to resist her blows.