 So it is controversial, though common, to say that rigidity assures that the proposition Hesperus = Phosphorus is necessarily true and a posteriori. On the other hand, it may be less problematic or less controversial to say that rigidity assures that the sentence or statement (interpreted sentence) ‘Hesperus = Phosphorus’ is necessarily true even though we can find this out only a posteriori (Fitch 2004, pp. 110–13; Hughes 2004, pp. 106–7; cf. Kripke 1980, pp. 20–1). If it is tenable to say that rigidity assures that some sentences or statements like this are necessarily true though a posteriori, further questions immediately impose themselves. Here is a salient question: Does the aposteriority that characterizes the necessarily true statements retain its epistemological significance and surprise, given that it is associated with statements rather than propositions? The question carries some importance in view of the popularity of Millianism; yet despite all of the debate about the correctness of Millianism, the question has been neglected.