Googling and my previous reading hasn't helped me here. Without meaning to give anyone a research assignment, I wonder whether any of my erudite readers have links or book-citations to answer the following questions:
1. History. Who first used the Sola's? What was the earliest documented use?
2. Latin -- that is, the Latin form and meaning of the Sola's. I know some Latin words and phrases, but have not studied Latin per se. You see (for instance) both solus Christus and solo Christo. What is the grammatical difference, and why are there two? Is it "Grace alone," as subject, or (as some say), "by grace alone"? That is, are some of the phrases grammatically equivalent to Greek instrumentals? Are they all nominative, do they vary?
This is background work for a sermon I have been invited and plan to preach on the Sunday before Reformation Day. Thanks in advance.