Are there any hints of the theme of "gospel partnership" to be found even in the very first paragraph of Philippians? Well, we can't tell unless we know what the standard opening of an ancient letter looked like.
The letter opening back in that day contained three elements: (A) the sender, (B) the recipient(s), and (C) a greeting. Here's an example from the Septuagint.
This reads, "King Nebuchadnezzar to all the people, tribes, and languages in all the earth. May peace be multiplied to you!"
Now, when we come to Phil. 1:1-2, we might expect something like this:
We could render this as, "Paul to the church in Philippi. Greetings!" However, Paul often expanded or modified the conventional formula and fill it "with matters of great mutual concern to himself and the community to which he writes ..." (Hawthorne, p. 13).
Here's the deal. We're so familiar with the opening paragraph of Philippians that it's easy for us to overlook its unique contents. By paying attention to the small details, we'll get a better handle of the message Paul is "telegraphing" to his readers.
Care to give it a try?