  Prior arrived at another important insight in the penultimate chapter of The Craft. Early in 1951 he read von Wright’s article ‘Deontic Logic’ and in ‘Modality’ he gave a cameo discussion of this area. His reading of von Wright reinforced in his mind an idea that he had come across in Peter of Spain, Isaac Watts, and the Port Royal Logic, an idea that was to be of considerable significance for his own future work. What von Wright called the ‘alethic’ modes—necessity, possibility, impossibility and contingency—are members of an extended group of concepts that includes the epistemic modes (‘it is known that’, ‘it is not known to be false that’, etc.), the doxastic modes (such as ‘it is believed that’), and the deontic modes (which include ‘it is permitted that’ and ‘it is obligatory that’). In The Craft Prior also listed Watts’ ‘it is written that’ and ‘it is said that’, noting that ‘one could think of innumerable others’ (1951: 749). Later, von Wright was to draw attention to what may be called the agentive modes: ‘the agent brings it about that’, ‘the agent makes it true that’, and the like (von Wright 1963).