The human race seems to make intellectual progress at a very slow pace. Even when progress is made centuries can go by without the new ideas becoming widely known.

Herewith my biased list of the milestones in thought over the past millennium or so.

1. The shift of the earth from the center of the universe (Copernicus, Galileo and Kepler).

2. The laws of gravity as a replacement for the celestial sphere (Newton).

3. The separation of superstition from historically informed religion (Spinoza).

4. The removal of the concept of a supernatural being as the creator of the universe (various people, let's choose Voltaire as representative).

5. The laws of electromagnetism (Maxwell).

6. The understanding of evolutionary processes (Darwin).

7. Relativity (Einstein).

8. Quantum theory and uncertainty (Heisenberg, and about a dozen others).

9. The framing of ethics without reference to a supernatural origin (John Rawls).

10. The structure and operation of DNA (Watson, Crick and followers).

11. The concept of a secular society (Jefferson and a few colleagues).

These can be roughly grouped into three areas. The first changes our conception of ourselves as part of the universe. The second shows how the world is based upon rational laws, even if some of them turn out to have a probabilistic element. The third puts the organization of society and its ethical basis back into the lap of the people and not based upon some supernatural foundation.

This is a pretty small list for nearly a thousand years. Even so, a large percentage of the planet still believes in the supernatural and the need for ethics to be based upon external sources. Many, even in developed countries, fail to understand the scientific method and the status of discoveries made using it.

Finally we have not yet come up with a set of ideas which will organize human behavior so that "might makes right" is not the ultimate way disagreements are handled. The lack of such an advance has cost the human race over 100,000,000 deaths in just the last 100 years alone. As our ability to destroy continues to increase, our lack of ability to control ourselves becomes more and more dangerous.