From the introduction:
Welcome to the Third Dawn Campaign Setting, a world of psionic power, swashbuckling action, and political intrigue, designed for the world’s most popular role-playing game. This product is somewhat unique in that it is truly an all psionic campaign setting. In the Third Dawn Campaign Setting, you will not find gods or goddesses; you will not find bards, clerics, druids, wizards, sorcerers, or paladins. Indeed, the Third Dawn Campaign Setting only has psionic and non-magical classes. Instead of the cleric, you can find the worldthought medic. In place of the wizard, you have the psion. And instead of the bard, you will find the thoughtsinger.