6 ideas
Pardoning a crime against the state encourages imitators, so the leniency meant to spare one person ends up costing many lives and much disorder later. Punishing the first offender firmly and publicly removes the incentive for others, which makes severity toward faction the more merciful policy for the realm as a whole.
A state holds together through two instruments: timely reward for service and certain punishment for fault. If either is withheld or applied unpredictably, subjects stop linking their conduct to its results, and discipline breaks down whatever the laws say.
A minister should be judged on capacity, probity, courage to tell the ruler unwelcome truths, and application to work. Probity without capacity is useless and capacity without probity is dangerous, so a ruler must test for both. He should prefer a few able counsellors to many who give conflicting advice.
A plan made known before it is carried out lets rivals and factions organise against it, so secrecy is an operational necessity and not a vice. Business of state should be confined to the few who must execute it, because each additional confidant multiplies the chance of a leak.
A ruler should govern by reason and not by passion, affection, or momentary pity, because decisions driven by feeling cannot be defended consistently. Anchoring choices in the lasting interest of the state gives a ruler a standard that can overrule personal sympathy and courtly pressure.
A state divided by armed internal factions, such as the Huguenot strongholds and rebellious grandees, cannot project power abroad because enemies will exploit the division. The sequence is to strip factions of their independent military and political bases first, then pursue greatness in foreign affairs.