Graham (left) and Crawford, sitting on a beach log in the film's opening scene.
The name 'Jack' is derived from Jackin (earlier Jankin), a medieval diminutive of John.[a] 'John' is an English form of Iohannes, the Latin form of the Greek name Ιωαννης (Ioannes), itself derived from the Hebrew name Yochanan, meaning "YAHWEH is gracious." "[The name John] owes its popularity to two New Testament characters, both highly revered saints. The first was John the Baptist, a Jewish ascetic who was considered the forerunner of Jesus Christ. The second was the apostle John, who was also supposedly the author of the fourth Gospel and Revelation."[b]
The name symbolism of 'Jack' indicates that Jack Crawford represents John the Baptist.
a. Behind the Name, 'Jack'. Web, n.d. URL = http://www.behindthename.com/name/jack.
b. Behind the Name, 'John'. Web, n.d. URL = http://www.behindthename.com/name/john.