Chapter 1. Introduction (Jacek Malinowski and Rafał Palczewski).- Chapter 2. Biogram (Janusz Czelakowski).- Chapter 3. Section of logic in Łódź 1982–1992 (Jacek Malinowski).- Part 1: Surveys.- Chapter 4. Janusz Czelakowski’s research on the theory of matrices and its applications in the seventies and eighties of the 20th century (Josep Maria Font and Ramon Jansana).- Chapter 5. A gentle introduction to the Leibniz hierarchy (Tommaso Moraschini).- Chapter 6. Czelakowski’s work on quasivarieties (Miguel Campercholi and Diego Castaño).- Chapter 7. On J. Czelakowski’s contributions to quantum logic and the foundation of quantum mechanics (Davide Fazio).- Chapter 8. Actions and deontology: Janusz Czelakowski on actions and their assessment (Fengkui Ju and Piotr Kulicki).- Part 2: Research.- Chapter 9. Assertional logics and the Frege hierarchy (Hugo Albuquerque and Ramon Jansana).- Chapter 10. Characterization of strong day implication systems (Sergey Babenyshev).- Chapter 11. SCI – Sequentcalculi, cut elimination and interpolation property (Andrzej Indrzejczak).- Chapter 12. Some more theorems on structural entailment relations and non-deterministic semantics (Carlos Caleiro, Sérgio Marcelino, and Umberto Rivieccio).- Chapter 13. Boolean-like algebras of finite dimension: From Boolean products to semiring products (Antonio Bucciarelli, Antonio Ledda, Francesco Paoli, and Antonino Salibra).- Chapter 14. Logic of action from the perspective of knowledge representation (Andreas Herzig, Emiliano Lorini, and Elise Perrotin).- Chapter 15. Implication in sharply paraorthomodular and relatively paraorthomodular posets (Ivan Chajda, Davide Fazio, Helmut Länger, Antonio Ledda, and Jan Paseka).- Chapter 16. My final comments to the volume (Janusz Czelakowski).- Chapter 17. List of publications of Janusz Czelakowski.