 Abelard was interested in the question of whether the present truth of statements about future contingent events are themselves determinate; i. e., whether “The sentence ‘Socrates will eat tomorrow’ is true”, if true, is determinately true. Denying this, he restricted the principle that all past and present true propositions are determinately true. Abelard also distinguished between determinateness and certainty. Future contingent propositions may be certain if they are revealed by angels, for example, but they are not knowable of themselves and not determinately true. (See Glossae super Peri hermeneias IX.19–42; Dialectica 211.32–212.23; Lewis 1987.)