Contents: Introduction; (1) The Libraries of Tycho Brahe & of Paul Wittich: The Misleading Attribution of the Copernican Annotations; Master Paul Wittich; Tycho’s Attempts to Acquire Wittich’s Library; & The Prague Tychoniana; (2) Wittich’s Copernican Annotations: Reinhold’s Annotations & the Liege “De revolutionibus”; The Vatican Wittich Copy; The Prague & Wroclaw Wittich Copies; & Why Annotate Four Copes of “De revolutionibus”?; (3) Reconstructing the Universe: Tycho’s Early Transformations & Wittich’s Visit; A Theft in the Castle?: Thycho’s “Legal Brief” on the Ursus Affair, & Ursus’ Account & Kepler’s Interpretation; & Constructing Tycho’s Cosmology. Appendix: The Vatican Annotations; & Wittich’s Obituary in ”Silesia Togata.” Illus.