“There would be something unreal about Jesus if we thought of him acting out, as it were, a part according to a script already written. This would contradict what we have learned already about his vocaton — indeed, it would contradict his genuine humanity. It may be that Jesus went up to Jerusalem hoping that things would turn out differently from the way they did. But there must have come that moment when he finally realized that faithfulness to his vocation meant death, and when he accepted that, and it is that moment that is represented to us in the mystery of the agony in the garden. Like the other mysteries, this one is partly recollection, partly interpretation, and both of these strands constitute its theological significance and truth.
(From Principles of Christian Theology, XIII.56.viii
Read it all: John Macquarrie