Mysterium Cosmographicum

Kepler, Johannes. Mysterium Cosmographicum (The Cosmographic Mystery [also translated Cosmic Mystery, The Secret of the World, and similarly]). 1596/97.[1] Tübingen: George Gruppenbach, 1597, rpt. 1621. For full title page: [2]

Full title runs, in Latin, and translated into English in Wikipedia citation:

Prodromus dissertationum cosmographicarum, continens mysterium cosmographicum, de admirabili proportione orbium coelestium, de que causis coelorum numeri, magnitudinis, motuumque periodicorum genuinis & proprijs, demonstratum, per quinque regularia corpora geometrica 
(Forerunner of the Cosmological Essays, Which Contains the Secret of the Universe; on the Marvelous Proportion of the Celestial Spheres, and on the True and Particular Causes of the Number, Magnitude, and Periodic Motions of the Heavens; Established by Means of the Five Regular Geometric Solids).[3]

See for the second known published defense of the Copernican heliocentric theory and, relevant here, a geometrical universe presaging or explicitly asserting the image of the mechanical, "clockwork" universe.

From Maria Popova, BrainPickings: "How Kepler Invented Science Fiction and Defended His Mother in a Witchcraft Trial While Revolutionizing Our Understanding of the Universe" (lightly edited, link given at end of quotation):

Three centuries before Kepler, Dante had marveled in his Divine Comedy at the new clocks ticking in England and Italy: “One wheel moves and drives the other.” This marriage of technology and poetry eventually gave rise to the metaphor of the clockwork universe. Before Newton’s physics placed this metaphor at the ideological epicenter of the Enlightenment, Kepler bridged the poetic and the scientific. In his first book, The Cosmographic Mystery, Kepler picked up the metaphor and stripped it of its divine dimensions, removing God as the clockmaster and instead pointing to a single force operating the heavens: “The celestial machine,” he wrote, “is not something like a divine organism, but rather something like a clockwork in which a single weight drives all the gears.” Within it, “the totality of the complex motions is guided by a single magnetic force.” It was not, as Dante wrote, “love that moves the sun and other stars” — it was gravity, as Newton would later formalize this “single magnetic force.” But it was Kepler who thus formulated for the first time the very notion of a force — something that didn’t exist for Copernicus, who, despite his groundbreaking insight that the sun moves the planets, still conceived of that motion in poetic rather than scientific terms. For him, the planets were horses whose reins the sun held; for Kepler, they were gears the sun wound by a physical force.[4]

RDE, Initial Compiler, 27Dec19