Returning to the language of the thanksgiving in 1:3-8, Paul resumes what he began in 4:10, moving it a step forward. In verse 10 he joyfully received the Philippians' gift as tangible evidence that their concern for him had "blossomed afresh." Since their gift met his material needs during imprisonment, it serves as evidence of their being "partners with him" (synkoinoneo) in his "affliction" (thlipsis; NIV share in my troubles); in verses 15-16 it is likewise evidence of their partnership with him in the work of the gospel. As in 1:5-7, their love for Paul and serving the cause of the gospel blend. After all, to love Paul is to love the gospel. But also as in the preceding paragraph, he qualifies what he says about the gift itself; again, it is not that he is not grateful (4:18-20 makes that abundantly clear) but that the gift is secondary to their relationship, in this case expressed in terms of how their gift to him is seen from above—a point that gets full elaboration in verses 18-19.
To speak of their gift in terms of "being partners with him in his affliction" echoes both his and their "participation in Christ's sufferings" (3:10) and the mutuality of their suffering together from 1:29-30 and 2:17—although in this case the emphasis is on their succoring him in his time of need. The language it was good of you (4:14) also appears on a regular basis in letters of friendship in reference to a benefit that one has received from the other.
The use of koinonia language in verse 14 in turn brings Paul back to the first use of this word in 1:5 (their "participation/partnership with him in the gospel"), but now with specifics. Indeed, the next sentence (4:15-16) holds the key that unlocks many of the mysteries of our letter. Four important reminders are noted. First, you Philippians . . . shared (aorist of koinoneo) with me in the matter of giving and receiving uses the technical language for the mutual giving and receiving of benefits in Greco-Roman friendship. Second, this "partnership" is related to the gospel and goes back to their early days; third, they are the only church that has entered into this kind of "partnership" with him (not one church . . . except you only). And fourth, the earliest evidence for it occurred at his very next stop in Macedonia, in Thessalonica, where you sent me aid more than once when I was in need. Unpacking these four items will tell a lot of the story between Paul and this church—and other churches as well.
First, the crucial matter is Paul's metaphorical use of commercial language that begins here and goes through verse 18: the matter of giving and receiving (v. 15); what may be credited to your account (v. 17); I have received full payment (v. 18). This sudden proliferation of commercial language has long been recognized; only recently has it also been recognized that well before Paul came by it, the language of verse 15 had been co-opted by the philosophers to express the reciprocity of benefits—the matter of giving and receiving—in true friendship. In the Greco-Roman world one could not understand genuine friendship without friends' benefit to one another; hence goodwill included mutual "benefits." But since benefits could easily deteriorate into something more utilitarian, Seneca, for example, actually wrote treatises on benefits, both to expound on their nature and necessity and to safeguard them from such deterioration. "Benefits" simply meant that friends could be counted on to help each other out, often at some degree of personal sacrifice—by caring for family, for example (see the sample letter on p. 14, or coming to one's aid in time of need or crisis, or embarking on activities that were of mutual benefit.
The language that had become common parlance for this social phenomenon was borrowed from the world of commerce, which is what Paul is now picking up. His use of this technical language in conjunction with koinonia in this matter implies a friendship agreement that both sides have intentionally entered into. The rest of his plays on the commercial dimension of the metaphor are his own.
Second, as already noted in the thanksgiving (1:5, your partnership in the gospel from the first day until now), this relationship goes back to the beginning, and thus to the early days of your acquaintance with the gospel (literally "in the beginning of the gospel when I set out from Macedonia"). Although there is some stickiness here in terms of details, together with 1:5 this passage makes clear that the friendship existed while Paul was first among them; it later became a bond between them, as this passage (cf. 1 Thess 2:2) and 2 Corinthians 11:8-9 make certain. This is what leads him in Philippians 4:10 to mention the hiatus, and now renewal, of this partnership.
Third, that not one church . . . except you only entered into this relationship with Paul can be taken in at least two ways: as a pejorative swipe at other churches or as a way of reminding the Philippians of the unique relationship he had with them. In light of the evidence especially from 1 and 2 Corinthians, where that church also wanted such a relationship but it was not granted (1 Cor 9:1-18; 2 Cor 11:7-11), the latter of these is surely the more likely. Why Paul chose such a relationship with this one church only is a matter of speculation, most likely related both to his choice to maintain himself hereafter by "working with his own hands" (1 Cor 4:12; 2 Thess 3:6-12) and to the special relationship he had developed with this first Christian congregation on European soil.
Fourth, this relationship, in which their part of the reciprocity was to minister to Paul's physical needs while his was to let this be their way of partnering with him in the advance of the gospel, began even when I was in Thessalonica. According to 1 Thessalonians 2:2, his early memory of his time in Philippi had also to do with his suffering and ill treatment there by the authorities; according to Acts 17:1-7, similar ill treatment happened again in Thessalonica—under the charge of treason. So the Philippians' material help during those rough days is now fondly recalled, this time in terms of his need. That they gave such help "more than once" (the NIV's again and again stretches the idiom a bit) indicates the level of their commitment to him in this matter.
But just as in Philippians 4:10-13, this mention of his need immediately calls forth another not that qualifier against possible misunderstanding. His short recital of their exemplary history of friendship with him in the matter of giving and receiving is not to be taken as an indirect request for more help. Exactly the opposite, and now picking up on the commercial metaphor itself, what he "seeks" (NIV looking for), he tells them, is (literally) "the fruit that increases into your account," by which he means metaphorically "an accrual of `interest' against your divine `account.' "
When unpacked, the metaphor expresses Paul's real concern for them, found as early as 1:25 in terms of "your progress in the faith." Their giving to him is an expression of love, of the gospel at work in their midst. For Paul every time they do so, it is also evidence of "fruitfulness," of the kind for which he prayed in 1:11. Such fruitfulness has the effect of being entered on the divine ledger as "interest," as the certain indication of the increase of their fruitfulness, which will find its full expression at the coming of Christ. They themselves will be Paul's eschatological "reward" (2:16; 4:1); their gift to him has the effect of accumulating "interest" toward their eschatological reward. Their gift, which serves his physical health, serves more significantly as evidence of their spiritual health. What else would one seek, one wonders, in a relationship such as theirs, which is predicated altogether on their mutual belonging to Christ?
Many years ago I heard a wise preacher counsel some younger ministers that Satan has three hounds with which he pursues those in ministry: pride, money and sex. Money is surely not the least of these. It is therefore of some interest for us to note how sensitive Paul is on this matter. He can scarcely speak about it, and especially his relationship to receiving it, without offering a demurral such as one finds in verse 17. This may well account for his (apparent) change of policy when he got to Thessalonica. There were enough itinerant religious and philosophical hucksters about, who according to Dio Chrysostom "used flattery as a cloak for greed" (cf. 1 Thess 2:4), for Paul to set out on a different course of maintenance upon leaving Philippi. Thus he can remind those in both Thessalonica and Corinth that his motives were totally free of pecuniary interests (1 Thess 2:1-10; 2 Cor 12:14-15). Paul did not "seek what is yours, but you" (2 Cor 12:14)—a paradigm for all who are in Christian ministry of any kind.