His teeth were half bared. His rigid body, clenched fists, and head drawn between his shoulders, all attested to a fierce hate breathing from every pore.
Moreover, we feel some quality of necessity about the proposition 'two and two are four', which is absent from even the best attested empirical generalizations.
Vampirism was a recognised condition attested by large numbers of witnesses and had characteristic signs and symptoms, such as corpses having fresh blood running through their veins.