Kikuchiyo may have a long way to go before he's a samurai, but at least he understands the ground rules before he starts.
GOROBEI: The threshing is all done. The bandits haven't come. They're beginning to think they've gone away.
KAMBEI: Yes. But when everything seems so peaceful, that's the most dangerous time of all.
First rule of warfare: the enemy can attack at any time, so don't be lulled into a false sense of security. Kambei is demonstrating what he brings to the table when he's hired to save this village. Being a samurai means much more than being able to fight.
KAMBEI: Well, a good fort needs a gap, a break. The enemy must be lured into
it. We couldn't keep this place only by defending it.
Another chunk of tactical brilliance. He's setting up the big finale, but he's making sure we understand why it's going to work and what the samurai are hoping to achieve with it.
GOROBEI: From the very beginning we're going to work in formation. We're going to harvest together and no one is going to go off and work by himself. From tomorrow on, we're going to camp together, unit by unit. So remember, from tomorrow on, no one is going to do anything by himself.
If order for this to work, the peasants need to learn to fight, and more than anything else, that means teamwork. Cue the theme to Rocky: we got some training to do!
MOSUKE: Now throw down your spears. It's useless to carry a spear to protect someone else's home when you can't protect your own.
Whatever happens to the individual characters, Seven Samurai makes it clear that you have to fight for what's yours sometimes, even if you might not be ready for it.
KAMBEI: There are only three houses beyond the bridge and there are twenty in the village. We cannot endanger twenty because of three.
Basic tactics here have repercussions in the story, since the old man opts to return to those buildings rather than stay with the rest of the village. Seven Samurai is very good at making sure we understand how military thinking affects the plot.
KAMBEI: There are only thirteen left, so we're going to let them all in at once. As soon as they pass us, we'll follow and trap them inside. This is the final battle. It will decide the outcome.
Normally with something like this, the film would refrain from talking about it beforehand, so as not to spoil the surprise. Kurosawa takes the opposite route here because he thinks that the need for us to understand the military strategy involved was more important than a dramatic surprise.
GOROBEI: I thought I told you to let us go, did I not? To think that instead you would choose your own death.
Death is omnipresent here. In warfare, you're only as good as the choices you make. There's a subtle nod to the link between the killers and the killed here. The fact is that the guy who kills you shares a bond with you that no one else in the world has. It's twisted, but that's reality, especially in a world like this.
KAMBEI: War is like that. If the defense is for everyone, each individual will be protected. The man who thinks only of himself, destroys himself. From now on, such desertion will be punished.
Military tactics depend on an inherent selflessness: valuing the whole community above yourself. Kambei is telling them that because it makes sense, but also because he knows it's the only way they're going to win this thing.
KAMBEI: Once again, we have survived.
Survival isn't necessarily the goal of war, he's suggesting. Dying a noble death, sacrificing yourself for a larger cause, and/or keeping innocent people safe might be worth sacrificing your life for. It also suggests that if you survive a war, you still have to live with the scars and psychological wounds. That's rarely an appealing prospect.