When Rhea gave birth to Zeus, she put him in a cave, located at Mount Ida on the island of Crete, so that his father Cronus wouldn't be able to find him and swallow him, which he had done with his previous children. In the cave, the goat Amalthea took care of Zeus and nourished him with her milk until he was grown up.
One day, as young Zeus played with Amalthea, he accidentally broke her horn. To make up for it and as a sign of gratitude, Zeus blessed the broken horn, so that its owner would find whatever he desired in it and the power to never run out of it. Later, the horn was filled with flowers and fruits, and given as a present to Zeus. It became known as the Horn of Amalthea, an eternal symbol of abundance.