 In The Theory of Probability, modal necessity is identified with universal quantification and possibility is identified with joint existential quantification of a propositional matrix and existential quantification of its denial. At least the spirit of this account is retained in Reichenbach’s later discussions of modality. His account of modality in Elements of Symbolic Logic (1947c) was developed as a separate work in Nomological Statements and Admissible Operations (1954e), and is the basis for his discussion of possibility and necessity in his essay on freedom of the will. Completed before his death and published soon after, Nomological Statements and Admissible Operations was reissued in 1976 under the title, Laws, Modalities and Counterfactuals, with an invaluable expository foreword by Wesley Salmon. Reichenbach’s own presentation is a nearly impenetrable mix of conditions on truth, entailment, logical form, and verifiability, which surely contributed to its lack of influence. Little if any discussion of it is to be found in the decades of literature on conditionals and counterfactuals since its publication.