Agent : acting seems right to me
Confident : bragging seems good also
To be honest it is a very ornate passage. It is impressive but it is not the sort of English that I personally enjoy reading. For me English is at its most powerful when it is clean, terse and sharp. George Orwell is an author that I would recommend if you are interested in that.
Maybe a slightly cleaner way of expressing the sentence, if I have understood it correctly, might be:
"When grounded in the present the soul will manifest itself through actions, not by mere intentions"