 In the context of (T), Heytesbury discusses the casus where an agent sees a person who looks exactly like a king, but is not one. The agent can believe the man to be a king beyond any doubt and even believe himself to know that. But, by (T), he knows neither that the man is a king (because that is not true), nor that the man is not a king (because he does not believe that) ([RSS] 1494: fol. 13vb [1988b: 447]). Even though Heytesbury does not explicitly say so, it seems natural to assume that this agent does not know that he failed to know that man is a king. Hence, he fails to know something, but also, presumably, fails to know that he fails to know it, which is a counterexample to negative introspection. Accepting the positive introspection while denying the negative introspection is based on Heytesbury’s interpretation of knowledge as an evidence-based act of considering something and apprehending its factuality: the absence of knowledge alone does not constitute conscious ignorance.