Pillars of Hercules

Much of the end of Canto 4, Book 1, takes up images of the spiritual quest as illustrated, for example, by Jason and the Argonauts’ quest for the Golden Fleece or the Labours of Heracles.

Or passing through a gate of pillar-rocks,
Venturing not yet to cross oceans unnamed
And journey into a dream of distances
He travels close to unfamiliar coasts
And finds new haven in storm-troubled isles,
— Book 1 Canto 4

The ‘gate of pillar-rocks’ most probably refers to the two Pillars of Hercules, which marked the limits of the achievements and possibilities of transformation known in ancient Greece.

It was Heracles who planted them at the end of the Labour of the Belt of the Queen of the Amazons, the symbol of the full mastery of the vital, or at the very beginning of the Labour of the Herds of Geryon, the symbol of the recovery of the divine gifts of life, which is also the first of the labours to take place in a mythical location. The poet Pindar, (5th century B.C.) speaks of it thus:

It is no longer easy to cross further the impassable sea beyond the columns of Heracles, they whom the Hero-God has set down as witnesses of the farthest navigation; he had tamed the monstrous beasts in the open sea, and he spotted exactly the currents of the muddy shallows, and he descended until he obtained the vision that leads to the return, and he made the land known.