Because Christianity is an historical religion, based on events in time and place, it is assumed too often, even by Christians, that those events are historically verifiable. Because we can point to classical references to a sect which believed in Christ, many jump to the conclusion that that belief is objective evidence of the facts they wish to establish. But history comes in later and in a different way.
What is inescapable for the most sceptical historian is not the fact of the Incarnate Body of Christ, but the fact of his Mystical Body, the Church. Whether or not on a particular Thursday evening in an upper room in Jerusalem, Jesus of Nazareth ordered His followers till the end of time to eat his Body and drink his Blood under the species of bread and wine can never be ‘historically’ established. But that for nineteen centuries this has been done cannot be ‘historically’ escaped.
… The unique phenomenon in history is the Church—that is to say, the company of people which no man now can number who eat, have eaten and will eat the Body, who drink, have drunk and will drink the Blood.
— Hugh Ross Williamson, The Great Prayer: Concerning the Canon of the Mass (1955)