In the course of his closing remarks at the Copenhagen Congress, the then President of the Association International des Études Byzantines reminded those who worried about the state of our field of “the rule that science may begin with imagination but … rests on factual documentation rather than conjecture”. As one who was (and is) less troubled about the way things were (and are) going, an art historian may be permitted to point to an example in which a document can be shown to corroborate educated guesswork, and consequently to demonstrate one way in which peace between the two camps can (at least on this occasion) be achieved. The result may not be the absolute certainty demanded by our ancien président, but it comes as close to proof as anything available in a domain notorious for its lack of “factual documentation”. The method in question is triangulation—a third datum brought to bear on two previously known bodies of evidence—and the example that of the Middle Byzantine silks that display images of eagles. At issue is the belief that surviving examples were originally gifts offered to foreigners who in turn presented them to institutions or individuals of the Latin church.