Briefly, my thesis traces the history of the problem of proving (or not) that the solar system is dynamically stable over a long period of time (like geological eras), between the publication of the Principia of Newton (1687) to the works of Laplace (1787).
The early period (until about 1760, actually) was concerned with the idea that the interplanetary medium offered some resistance to the motion of the planets, and that through this resistance, the planets would eventually spiral into the sun. (As this would involve the total destruction of the entire solar system, the Earth, and life itself, most would consider this to be a bad thing, though for some, it was consonant with their theological beliefs.)
Thereafter, Joseph Louis Lagrange and later, Pierre Simon Laplace, set about to show that the gravitational interaction between the planets would not disrupt their regular motion around the sun. Though Laplace is usually given credit for the first "proof" that the solar system is stable, a portion of my thesis is devoted to showing that much of Laplace's work is either based on Lagrange, or is anticipated by Lagrange, who is shown on the right.
For more on my thesis, you can download it. In one of the appendices (called chapter12.tex) I have one of my few original contributions to mathematics: a purely geometric demonstration of the equilateral solution to the Lagrange problem, using Newtonian methods. When I think enough people have HTML 3.0 capable browsers, I'll have more pages on line.