SOURCE: "An Early Instance of Deductive Discovery: Tycho Brahe's Lunar Theory," in Isis, Vol. 58, Pt. 1, No. 191, Spring, 1967, pp. 19-36.

In the following excerpt, Thoren probes the gradual, deductive creation of Brahe's theory of the moon.

Of all the projects undertaken by Tycho Brahe in his redintegration of astronomy, his researches on the lunar theory proved far the most fruitful for him. As a result of his perseverance in the study of the moon's motion, he succeeded in adding four new inequalities to the theory that was already the most complicated of the orbital representations, thereby reducing its discrepancies by a factor of about five. It is with Tycho's discovery of two of these inequalities—the inequalities in latitude—that this paper is concerned.

When Tycho began his researches on the lunar theory in the early 1580's, the existing model of the moon's motion in latitude was about two...