A teacher cleared off his desk and placed on top of it a few things. One of them was an empty mason jar（玻璃瓶）. He filled the jar with golf balls until he could fit no more. He looked at the classroom and asked his students if they agreed that the jar is full. Every student agreed that the jar was really full.
The teacher then picked up a box of small pebbles（卵石） and poured them into the jar with the golf balls. The pebbles filled all of the openings in between the golf balls. He asked the students if the jar was full. Once again, they agreed.
Now the teacher picked up a bag of sand and poured it into the jar. The sand filled in all of the empty space left between the golf balls and pebbles. He asked the class again if the jar was full. The students agreed again.
The teacher said, "I want you to know that this jar represents your life," he started. "The golf balls represent the important things: your family, health, friends…The pebbles represent the other things in life, such as your job, house and car. The sand is every small thing . If you put the sand in first, there is no room for the pebbles or golf balls.The same goes for life. If you spend all of your time on the small things, you will never have room for the things that are most important.
Pay attention to the important things in your life. You should know there will always be time to clean the house or go shopping.