There are many oppositions known to man. Some are just easier to see than others. For example, a man looks at an empty field and decides that he wants to plant it. So he picks up his hoe and works the field; after a while he becomes tired and realizes he is incapable of doing it by himseld, so he invents the plow. He is now able to work many fields in an easy manner. The opposition leads to the creation of a tool.
A person decides to travel from the east coast to the west coast. He/she realizes that there are many miles and much time opposing them, so they decide that instead of walking, they will ride a horse. Eventually the horse doesn't get them to their destination soon enough, so the train is invented. Then the car, then the airplane, and finaly, the supersonic jet.
The supersonic jet is opposed by the air thru which it travels. Therefore it cannot be boxy, it must be aerodynamic and capable of cutting thru air like a knife. The opposition sculpts the form.
Gravity opposes any upward force. The only way to counter it is through the use of a rocket with the capability to produce enough force to escape the Earth's gravitational pull. But even then, it will succumb to the pull of the sun. Gravity is on of the few force's incapable of being countermanded.