Why was His soul troubled?

(Octavius Winslow, "CONSIDER JESUS" 1870)

"My soul is overwhelmed with sorrow
 to the point of death." Mark 14:34

In this lay our Lord's greatest suffering:
His soul sorrow. Compared with this . . .
  the lingering, excruciating tortures of the cross,
  the extended limbs,
  the quivering nerves,
  the bleeding wounds,
  the burning thirst;
were, as nothing.

So long as our blessed Lord endured the gibes
and insults and calumnies of mere men, not a
complaint escaped His lips.

But, when the wrath of God, endured as the
Substitute of His people, entered within His
holy soul, then the wail of agony rose strong
and piercing, "My God, My God, why have
You forsaken Me?"

Why was His soul troubled?

He was now bearing sin and, consequently,
the punishment of sin; the wrath of God
overwhelming His soul. Divine justice, finding
the sins of God's elect meeting on His holy soul,
exacted full payment and inflicted the utmost
penalty!