Sun Tzu’s war theories are built on information and espionage. He believed a spy-master had to be very smart indeed, to sniff out the truth from mission reports. He also had to be highly thorough: when a military operation is mapped out, efforts must be made to gain knowledge about the opposing commander, his staff members, his aides-de-camp, his gatekeepers and his guards.

Sun Tzu clearly preferred fire to water in military tactics, and he developed quite a comprehensive theory on the use of fire. But if read between the lines, the arsonist's manual reveals much more on opportunities.

Sun Tzu studied the state of mind of soldiers. He noticed that they tend to grow stronger in solidarity as they venture deeper into enemy territory. When they're surrounded, they offer an obstinate resistance; when they're given no choice, they put up the toughest of fights; and in moments of desperation, they take to orders like thunder follows lightening.

Sun Tzu in his science of war also relied on observation to read the enemy’s movement, the meticulous and exhaustive approach with which he tried to gain information about the enemy can still be inspiring.

For a military commander, there are roads he doesn’t have to take; there are enemies he doesn’t have to fight; there are cities he doesn’t have to attack; there is territory he doesn’t have to occupy; and there are king’s orders he doesn’t have to follow. A commander must know he always has other choices and must make up his mind based on the situation at hand.

A commander must choose the battleground to his advantage and led his forces to the right spot before the enemy shows up.

Good communication is required for troops assemble and split up as the situation requires.

Commanders to stay clear of the enemy when they’re at their best, and attack only when the opponent is tired and hungry.

A commander must shape his army like water. Water shuns the high rocks and flows in the shallow valleys. Like water, a commander must direct his army away from the enemy’s strong points and strike at their weaknesses. Water takes various shapes according to the terrain; an army must adapt its strategies according to its enemy.

In Chinese, zheng refers to something that is fundamental; while ji means something odd or extraordinary. Sun Tzu believed that to be successful in war, there needs to be a balance between these two.

The best approach is to go after the opponent’s strategy and defuse their initiative to fight; the second-best course of action is to work for a diplomatic victory; physical confrontation is fine in the absence of smarter solutions; but siege warfare should only be the last resort.

Sun Tzu examined the social and economic cost of war, and the law of supply and demand. Wars are costly, and costlier still if they are prolonged, so it is best to move fast and aim for a quick victory.