If there is one person who has deepest understanding about what a free market is and why it is superior to the collectivism, it is Milton Friedman.

He showed that seemingly different activities like regulation, socialism, and nationalistic trade policy are basically the same things against the free market. And he explained why the free market is required for human freedom.

For me, Albert Einstein showed us that the world is not so simple. Even today, his theories are surprising to us. Time is relative. Gravity makes curvature in the space. The light is a particle as well as a wave...

As a non-scientist I don't think I fully understand his theories. But I feel his theories beautiful when I read popular physics books. it is clear that he opened our eyes in understanding the nature of the universe.

Peter Drucker is was a business thinker, but his thoughts go beyond just business.

Among others, I think his insights that innovation is the key function of a business, earlier than most other business and economics scholars, shows he was an innovator himself.