There’s not a lot of Grace in the Theravada tradition. By and large, the conception of the spiritual journey from a Theravada perspective is about taking personal responsibility to form oneself in ways which lead to Peace, Enlightenment, Nibbana. Similar to the tradition’s concept of Dukkha, I find the extreme emphasis on personally willing and causing our own formation to be somewhat one-sided. I think we also need Grace.
In the theistic contemplative traditions, the place of Grace is obvious. One is responsible for their own moral development, but also must open themselves to a transformation which can ultimately come only from God.
"Then why is this work so toilsome? The labor, of course, is in the unrelenting struggle to banish the countless distracting thoughts that plague our minds and to restrain them beneath that cloud of forgetting which I spoke of earlier. This is the suffering. All the struggle is on man’s side in the effort he must make to prepare himself for God’s action, which is the awakening of love and which he alone can do. But persevere in doing your part and I promise you that God will not fail to do his."
In non-Theravada forms of Buddhism, it is also easier to see the place of Grace. Dogen’s “just sit” and “your original face will appear” stand out from the Zen tradition. One opens themselves to something that has to “just happen.” It has to arise of its own. There is a back and forth between what we must do, and what must be done in and for us.
In the Theravada tradition, it seems to me that the most relevant Grace-related doctrine is the concept of Arising or Dependent Origination. Roughly speaking, the doctrine of Dependent (or Interdependent) Origination states that “when this happens, this will follow” , “when that happens, that will follow.”
“When this exists, that comes to be; with the arising of this, that arises. When this does not exist, that does not come to be; with the cessation of this, that ceases.”
– Assutavasutta, Samyutta Nikaya 12.61
The general idea of Dependent Origination seems to underlie much, if not all, of Theravada thought. If trsna/craving/thirst/desire is present, dukkha/suffering will follow. If one follows the Eightfold Path and thus eliminates trsna, dukkha will cease.
Specifically in regards to Theravada meditative practice, one can be diligent in their concentration practice, but the Jhanic states must arise. One can directly seek Nibbana, but the experience of Nibbana must arise.
The Theravada tradition tries to make systematic what one must do to attain Nibbana so much so that it seems to be presented as if the whole journey is completely within our control.
But it seems to me that Dependent Origination is itself a Grace. Arising itself is a Grace. It is something we can put ourselves in a position to experience, but the experience itself has to, in some sense, be done in us and for us.
Perhaps, from a Theravada perspective, the structure of the universe itself contains an element of Grace. It’s baked in.