Coffee's Priority

From a forward email:
A professor of philosophy came into his class with a glass jar, some rocks, pebbles, sand and a cup of coffee. Then he asked his students if all the ingredients would fit in the jar. Looking at the entire ingredients, most of them replied in the negative.
The professor proceeded to fill all the rocks in the jar. Then he took the pebbles and poured them in, while shaking the jar. They fit in the gaps between the rocks. The professor then looked up and asked what the students thought of it now. They had started smiling. The professor then proceeded to fill in the sand. It too, fit in between the pebbles. Then finally, the professor poured in the coffee, a perfect fit. One of the students got up and asked him the meaning of the experiment.
The professor replied – “The jar represents your life. The rocks represent your basic needs, the pebbles your secondary needs and the sand is tertiary needs. If you want to have everything in life, learn to prioritize correctly. If you go for your basic needs first, like family, friends and happiness and then for secondary needs as job and salary, you may be able to get even your superficial needs as societal position, recognition etc. Prioritize them wrongly, and your life isn’t enough to hold all of them.”
After a round of applause, another student said – “But professor, what about the coffee?”
“Oh that,” said the professor with a smile, “that just shows that no matter how full your life may be with your needs, always find an evening for a cup of coffee with a good friend. It fits in with everything.”