I. Truth-Logic and Modal Logic, p. 1 II. Some Elements of Truth-Logic. Quantification, p. 5 III. Alethic Modalities, p. 8 IV. Epistemic Modalities, p. 29 V. Deontic Modalities, p. 36 VI. Combined Modalities, p. 42 VII. Higher Order Modalities, p. 57 Appendix I. The Modal Syllogism, p. 78 Appendix II. The Axiomatic Systems M, M', And M", p. 84