The Wisdom of Gaia

The Wisdom of Gaia is a quest in Legend of Mana.

Solution
Enter Domina. Go to the Inn (the top left door in the center of town). Enter the room on the right on the bottom floor. Talk to Daena and say that Souls are Forever. Tell her that you will go with her to see Gaeus and she will join your party.

Enter Luon Highway and follow theses directions to get to Gaeus:

Right Right Lower Right at Fork Right Right Right

Talk to Gaeus and Daena will give the Forbidden Ring which will share experience with all of your party members.