Emmons is the world's leading expert on gratitude. You can check out a popular treatment of his research in his book Thanks!.
Toward the end of his talk, after reviewing the positive benefits of gratitude and how gratitude can be fostered, Emmons turned to more conceptual issues. One of the issues he raised was the distinction between gratitude for and gratitude to.
Gratitude is a social emotion, the thankfulness we feel having receiving a gift (or some benefit). Gratitude implies a gift, which in turn implies a giver. This is gratitude to.
But what about gratitude for? Emmons raised the question of environmental gratitude. Can you feel gratitude for the sunrise, a beautiful mountain, for life itself?
To be sure, we can feel lucky and fortunate for all these things. But without a giver can we, properly speaking, feel gratitude for these things?
In short, since gratitude is a social emotion might feelings of gratitude--environmentally and cosmically speaking--require a metaphysical framework? Gratitude to a giver?
And this isn't only about emotional states. When we feel grateful we take care of the gift, cherish it. Being grateful for the world and life prompts us to take care. By contrast, when we don't feel grateful we don't take care. In short, gratitude is associated with ethics.
So there is a reinforcing matrix here of metaphysics, gratitude and care.
Faith, worship and ethics.