An ancient pre-Christian legend inspired an iconographic motif associated with the Eucharist
A pelican, the story goes (as found in Physiologus, a text written by an anonymous Alexandrian author in the second century), in order to prevent its chicks from starving in times of scarcity, would pierce its chest with its own beak to feed them with its own blood. According to other legends, if pelican chicks happen to die, the pelican would open its own chest and bring them back to life, spraying them with his own blood.
In view of this existing tradition, it is easy to see why the early Christians adopted the motif as a symbol of Christ, the Redeemer who gives up His own life to bring his own back from the death of sin, feeding them with His own Body and Blood in the Eucharist.
Interestingly, St. Epiphanius, St. Basil and St. Peter of Alexandria quoted the Physiologus; Dante, in his Paradiso, refers to Christ as “our Pelican” and Shakespeare himself, in his Hamlet, through Laertes, refers to the legend of the pelican (“to his good friend thus wide, I’ll open my arms / and, like the kind, life-rendering pelican, repast them with my blood”). Even Aquinas, in his Adoro te devote, wrote: “like the tender tales of the Pelican / bathe me, Jesus Lord, in what Thy Bosom ran / Blood that but one drop has the power to win / all the world forgiveness of its world of sin.”