From a sermon by the late John Webster delivered at Christ Church Cathedral, Oxford, Maundy Thursday 2001.
... The memorial which is instituted tonight and which we are commanded to continue is a memorial not of the Last Supper, but of his death. Maundy Thursday is about Good Friday. And to continue week by week, day by day, to celebrate the Lord's Supper is to lodge at the heart of the Church the single fact of the death of the Lord.
This means, immediately, that there is an inescapable backward reference in every act of gathering for the Lord's Supper. The Christian Eucharist is a memorial. But what is a memorial? Clever theologians sometimes take me to one side with a kindly look in their eyes and explain to a poor benighted Protestant like me that in the Bible remembering doesn't mean calling to mind something past, but rather reactivating or re-enacting the past so that it's powerfully present among us now. But though I'm open to argument, I don't in the end think that's really right. It's not right because whenever we start talking in terms of making something present, we cannot avoid taking away from the uniqueness and unrepeatability of what happened on the cross. What do when we gather for Communion is not a re-enactment; it is a looking back to what took place once and for all.
... Celebrating Communion is thus not first of all about here and now, but about there and then; only because it's about there and then is it about here and now. That's why Paul calls it a proclamation of the Lord's death.
... Here, in this assembly at this table, God is at work. And God's work here is present to us, to make present to us, what took place on Good Friday. We don't make Good Friday real by reenacting it, or by thinking and feeling about it. God in this sacrament declares to us what Good Friday made true: that he is our reconciler; that sin is finished business; that we can repent because God has forgiven; that the promised acted out in the death of Jesus stands for all time and for each human person. In this memorial, God turns us backward; but he also makes present to us the limitless power of what the Son of God suffered.
... What then do we do now, as we assemble to remember? In one very real sense, we do nothing. That is, whatever we do does not in any way contribute to or supplement or finish off or make real what God has done ... What we do is therefore a strange kind of doing. It's doing in which we don't initiate , don't try to bring something about, don't try to make the world. It's a doing in which we receive and take into ourselves the gift of what God has already done. And that doing is called, very simply, faith.
John Webster, 'Take this Holy Sacrament', Confronted by Grace. Meditations of a Theologian ed. by Daniel Bush & Brannon Ellis (Lexham, 2015 ) pp.75-79.