Eric Alexander once gave a lecture at the Keswick Convention entitled “The Cup of Bitterness, and the Cup of Blessing.” In this talk he noted:
The supper is really a preview of the cross for the disciples, where they see it enacted before their eyes–as we do on occasion when we gather at the Lord’s table: a preview of the cross for them. But Gethsemane is essentially a foretaste of the cross for Him. There is a cup in the upper room there in Jerusalem which Paul delights to call, in the first letter to the Corinthians, “the cup of blessing which we bless.” “What shall I render unto the Lord,” asks the Psalmists, “for all His benefits toward me? I will take up the cup of salvation.” That is the cup that Jesus is offering to them–“Take, drink it,” He says.
But there is another cup, you will notice in these verses, a cup in Gethsemane; and that is the cup which Jesus calls “this cup”–“Father, if this cup may not pass from me except I drink it, Thy will be done.” And if the first cup in the upper room is the cup of blessing, and the cup of salvation which they are to drink, then the cup which Jesus looks upon there in the Garden, which makes the other cup possible, is the cup of bitterness and sorrow which He is to drink.
It seems to me that it is only when we have begun to understand something of the bitterness of the cup which He drank, that we can really discover what are the depths of the cup of salvation from which we have been finding we need to drink so deeply day by day. Now this experience of our Lord is a foretaste of the cross; for the whole ghastly spectacle of the sin of man is there before Him in this cup which comes before His eyes in Gethsemane, and the ingredients of His suffering and His agony on the cross.
In The Cross in the Experience of Jesus R.A. Finlayson made the observation that Jesus had to leave the peace of the upper room for the agony of the Garden. It was the cup of suffering in the Garden for Jesus that made the cup in the upper room a cup of blessing for us. Finlayson explained the contrast in the following manner:
Gethsemane is not a field for intellect, it is a sanctuary for faith. There was transacted something that brings us completely out of our depth, yet something that has such a distinct bearing on our redemption that we dare not pass it by. Here, in the innerness of His own experience, Christ knows what it is to be identified with the sinner, and to become Himself the sin-bearer.
Now it can be said that Gethsemane is for us quite a new introduction to our Lord. We recognize Him readily at the supper table in the upper room, where everything is calm, serene, untroubled; but from the calm serenity of the upper room, He plunged suddenly into the gloom and storm of Gethsemane, and the contrast is impressive. In the upper room you have a figure of composure and of singular spiritual strength, in the Garden you have a broken Man, distressed, in anguish, conscious of His weakness, pleading for the sympathy and the vigil of three disciples. What has happened? Just this, that He was entering more consciously into the full implications of His priestly office, and of His position as sin-bearer.