There’s a wonderful scene in Steven Spielberg’s movie LINCOLN. President Lincoln (Daniel Day-Lewis) asks influential representative Thaddeus Stevens (Tommy Lee Jones) for his support in an upcoming vote. Stevens, a radical abolitionist, is having none of it. He questions the people’s appetite for emancipation. Because of slavery, he says, “the inner compass that should direct the soul toward justice has ossified in white men and women.” Lincoln’s reply is brilliant:

A compass, I learned when I was surveying, it’ll… it’ll point you true north from where you’re standing, but it’s got no advice about the swamps, deserts and chasms that you’ll encounter along the way. If in pursuit of your destination, you plunge ahead heedless of obstacles, and achieve nothing more than to sink in a swamp… what’s the use of knowing true north?

These two men share a vision: they both want to see an end to slavery. They have significant differences of opinion about happens after they achieve it, but for now,​ they must help each other. More importantly, though, they also have different opinions about how to go about achieving their vision. While Stevens wants to charge full speed ahead, Lincoln prefers a more measured approach. He understands the second-order effects that would likely result from tackling the issue head-on.

In this scene, Lincoln articulates the spirit of cybernetics. In order to get somewhere, you must know where you’re going: You must have a vision of your desired goal and how the world will be different once you’ve reached it. But having a vision isn’t enough; you must also have a strategy and be open to adjusting​ as conditions evolve. You must take continuous readings of your surroundings: Where are you in relation to where you want to be? Are you still on track? Do you need to correct course? If so, you make a change; take another reading; correct course. Step by step, you find your way around the swamps, deserts, and chasms — always keeping true north in mind.