The converse does not hold


To land a cargo plane requires and airstrip, but an airstrip will not cause cargo planes to land.

When you fall asleep your eyes close, but closing your eyes does not make you fall asleep.

Good poise produces a straight spine, but straightening your spine will not give you poise. Inhaling quickly produces a sensation of wind through the nose, but a sensation of wind in the nose does not mean you are inhaling quickly.

Good programmers write comments, but writing comments does not make you a good programmer. Good programs are modularized, but modularization does not make a program good.

Depressed people frequently have low levels of seratonin, but increasing the level of seratonin will not therefore cure depression.

People who pass exams spend many hours studying, but spending many hours studying will not mean you pass your exams. Writing a thesis at some point involves sitting in front of a computer, but sitting in front of a computer will not cause you to write a thesis. People who do useful research publish papers, but people who publish papers only rarely do good research.

Free and peaceful countries hold elections, but an election will bring about neither freedom nor peace.

To achieve something often requires hard work, but hard work does mean you will achieve something.

Happy people work hard, but hard work will not make you happy. People who have a purpose in life work hard, but hard work will not give a life purpose.