And he took with him Peter and the two sons of Zebedee, and began to be sorrowful and very heavy. And he took with him Peter and the two sons of Zebedee - That is, James and John; the same persons who had beheld his transfiguration on the mount - that they might contemplate this agony in the light of that glory which they had there seen; and so be kept from being stumbled by a view of his present humiliation.
Began to be sorrowful - Λυπεισθαι, from λυω, to dissolve - exquisite sorrow, such as dissolves the natural vigor, and threatens to separate soul and body.
And very heavy - Overwhelmed with anguish - αδημονειν. This word is used by the Greeks to denote the most extreme anguish which the soul can feel - excruciating anxiety and torture of spirit.