Preface.- Chapter 1. Introduction.- Part 1. The Context.- Chapter 2. Jesuits and Science: A Long Tradition .- Chapter 3. Science and Theology in the Nineteenth Century.- Chapter 4. Angelo Secchi: A Man of his Time.- Part II. Angelo Secchi's Scientific Contributions.- Chapter 5. The New Collegio Romano Observatory.- Chapter 6. Angelo Secchi and the Development of Spectroscopy.- Chapter 7. Planetary Observations by Angelo Secchi.- Chapter 8. Angelo Secchi: Natural Philosopher and Instrument Innovator.- Chapter 9. Angelo Secchi and Meteorology in Italy.- Chapter 10. Something New about Angelo Secchi's Meteorographs.- Chapter 11. Angelo Secchi's Book on The Unity of Physical Forces.- Chapter 12. The Measurement of the Geodetic Base at Via Appia.- Chapter 13. The History of the Secchi Disk.- Chapter 14. Terrestrial Physics in Italy.- Chapter 15. Angelo Secchi and Gnomonics.- Part III. Some Later Issues.- Chapter 16. The Unachieved Angelo Secchi Monument.- Chapter 17. Astronomy in Italy after Angelo Secchi.- Chapter 18. The Specola Vaticana: Jesuit Astronomy Today.- Chapter 19. Astronomy in Rome after Angelo Secchi, and his Heritage at the Rome Astronomical Observatory.- Part IV. Current Resources.- Chapter 20. Angelo Secchi Archives.- Chapter 21. An Angelo Secchi Portal by INAF.- Chapter 22. GATE (Gregorian Archives Texts Editing): An Online Resource for Angelo Secchi Correspondence.- Index.