Just as no moss will gather on a stone which is continually rolling, so a man, who constantly changes his occupation or plan of life, will never succeed in life. A man who never settles down to anything long is a "rolling stone." Such a person makes little progress in life. To achieve success in business a man must choose a trade and stick to it. He will never succeed if he keeps changing his trade. To rise to the highest position in a profession, a man must stick to his job rather than change it every year. To become a great scholar, one must specialize in one subject rather than change from one subject to another.
What is an Expansion?
It's a sentence or a proverb or a saying that'll be given and then we need to enlarge it by adding illustrations, details regarding it, etc.