[15:17] 1 sn The purple cloak probably refers to a military garment which had the color of royal purple, and thus resembled a king’s robe. The soldiers did this to Jesus as a form of mockery in view of the charges that he was a king (cf. 15:2).
[15:17] 3 sn The crown may have been made from palm spines or some other thorny plant common in Israel. In placing the crown of thorns on his head, the soldiers were unwittingly symbolizing God’s curse on humanity (cf. Gen 3:18) being placed on Jesus. Their purpose would have been to mock Jesus’ claim to be a king; the crown of thorns would have represented the “radiant corona” portrayed on the heads of rulers on coins and other artifacts in the 1st century.
