Astrology as the study of gravity
The three most important points in a natal chart are the sun, the moon and the rising sign. I've tried to explain this before but it's rambly.The irrational belief that the Sun, the Moon and other heavenly bodies influence life here on Earth via invisible forces.Like gravity.
The rising sign marks one of the two horizons and is part of the House system. The Rising sign and House system tell you Earth's mathematical relationship or orientation in a geocentric map of the solar system.
So the most important influences in an astrological chart are the sun, the moon and the earth.
If you phrased it right, no one on earth would disagree that the sun, moon and earth are the biggest influences in the solar system on life on planet earth.
The personal planets are generally those closest to earth: Mercury, Venus and Mars.
Those have the strongest influence on individuals.
Then you have planets that rule relationships to the larger world, like higher education, law and government.
It's late, I'm tired, but the order of influence of planets roughly corresponds to how strongly their gravitational field would impact us here on earth.
Footnote
I don't know how to clearly express this, but the rising sign and house system describe the orientation of the earth in this map as it relates to the place and time of birth.
See also Retrogrades Revisited.