Mathematical Disquisitions: The Booklet of Theses Immortalized by Galileo offers a new English translation of the 1614 Disquisitiones Mathematicae, which Johann Georg Locher wrote under the guidance of the German Jesuit astronomer Christoph Scheiner. The booklet, an anti-Copernican astronomical work, is of interest in large part because Galileo Galilei, who came into conflict with Scheiner over the discovery of sunspots, devoted numerous pages within his famous 1632 Dialogue Concerning the Two Chief World Systems-Ptolemaic and Copernican to ridiculing Disquisitiones. The brief text (the original was approximately one hundred pages) is heavily illustrated with dozens of original figures, making it an accessible example of geocentric astronomy in the wake of the telescope.