How did Jean Le Rond d’Alembert explain the precession of the equinoxes?

Jean Le Rond d’Alembert explained the precession of the equinoxes and the related phenomenon of nutation in his 1749 work, Recherches sur la précession des équinoxes et sur la nutation de l’axe de la terre.1

By applying his own mathematical principles—specifically those developed in his Traité de dynamique—to the motion of bodies, d’Alembert was able to determine the characteristics of these celestial movements. His work was part of a broader effort by 18th-century mathematicians, including Leonhard Euler and Joseph-Louis Lagrange, to completely mathematize mechanics, reducing physical problems to axiomatic systems that could be solved through analytical methods.12

While Isaac Newton had provided the initial explanation for the precession of the equinoxes as a result of the gravitational influence of the Sun and Moon on Earth’s equatorial bulge, d’Alembert’s contribution was instrumental in further refining the mathematical understanding of these complex motions.341