Within ch. 6, this passage is transitional. Vv. 1-18, discussing as they do "the three pillars of piety," form a single unit. Vv. 25-34, united by the theme of "anxiety," rest upon vv. 19-24 (together with 1-18); note the "therefore" (dia touto) with which v. 25 begins. Moreover, vv. 19-24 are foundational for obeying Jesus' teaching both in vv. 1-18 and in vv. 25-34. For these verses concern the disciples' basic mentality, their basic view of the world and life (and beyond) - we might say their "metaphysics" - which affects and governs the way they look at everything.
Treasures Earthly and Heavenly. 6:19-21.
The reality of heaven. This is a fact which both Jesus and the disciples presuppose. Jesus does not have to begin by arguing that heaven is there, that it is real. Both he and the disciples have a true metaphysics, and heaven is integral to it. Heaven is affirmed as the dwelling-place of God the Father (6:9-10). Jesus preaches the coming of "the kingdom of heaven" (4:17). Heaven is a real place in which one may "store up treasures" (6:20).
The priority of heaven. Jesus commands that his followers should not store up treasures on earth, and that they should store up treasures in heaven. We know that his command does not proceed from the kind of dualism that denies the reality or the worth of earthly things. How could we think this, in view of 6:11, "Give us today our daily bread"? Jesus gives no support to a view that is totally world-denying (cf. Paul's assault on such a view in 1 Tim 4:3-5). So why does Jesus give this kind of command?
The durability of heaven. The permanence of heaven explains the priority of heaven. Earthly treasures are vulnerable both to destruction and to theft. Very likely the word usually rendered "rust," brosis, means "eating," referring to the moth's (or another insect's) eating holes in a garment, a parallel expression to the thief's "digging through" the wall of a house (cf. Gundry, 112; BAGD s.v. brosis). Neither poses a threat to the treasures stored up in heaven (v. 20).
The God of heaven. It is more than a concern for security that moves disciples to heed the commands of 6:19-21. The context (starting with 6:22-24) makes it clear that the laying up of heavenly treasure is motivated fundamentally by one's view of God. Heaven is heaven because God dwells there (v. 9). Therein lies heaven's appeal, durability and security. It is vital that one's heart (v. 21b) be set supremely on God himself (cf. below on 6:24). Otherwise the longing and striving for heavenly treasure poses a grave danger - namely that one become greedy for the heavenly treasure precisely because it is secure and durable. (Cf. the appeal of a stock market security which would both pay a relatively high rate of interest and be relatively risk-free.) In this case heavenly treasure would pose a graver threat to a disciple's heart, than would an earthly. The only safeguard against that, is a heart given utterly to God.
Eyes Good and Bad. 6:22-23.
The figure. Jesus speaks of an eye that is haplous, and of an eye that is ponaros. Ponaros means "bad, evil"; so of an eye, "bad" in the sense of "unhealthy, sick." Haplous basically means "single" (cf. diplous, "double"). In the present figure, as a parallel to ponaros, it means "sound"; unlike the ponaros eye, it fulfills its proper function. The sound eye serves as a "lamp of the body," in that it admits light into the body; the bad eye, correspondingly, prevents the light from illuminating the darkened body. (Think of a closed door, then an opened door allowing light into a dark room.)
The meaning. When does a disciple have a "sound" eye?
When he has the right understanding of history. He interprets history (past, present, and future) in the light of, and on the basis of, Jesus' declaration about the coming Kingdom of God. The present hiddenness of the kingdom, does not blind him to the present reality of the kingdom (cf. the parables of Mt 13). He correctly interprets "the signs of the times" (16:3). This perception in turn affects the way he views everything. On the other hand, the person who fails to perceive the truth about the kingdom - or who, having perceived it, rejects it (cf. the comments on 12:30-37) - will lack true understanding of everything else.
When he has the right understanding of God. To have the right perception of the kingdom, one must have the right perception of God. The kingdom is his; and its coming is his achievement, not man's (6:10). Viewing reality with soundness, means viewing it in the light of God - who he is (Lord of heaven and earth) and what he purposes to do (namely, establish his kingdom in the world).
Two Kinds of Slavery. 6:24.
The language. Significantly, the verb behind "serve" is not diakoneo ("to serve"), but douleuo ("to be enslaved to"). The corresponding nouns are diakonos and doulos respectively. In the ancient world, every doulos was a diakonos, but not every diakonos was a doulos. A diakonos could work for more than one master, but a doulos could not. Jesus says, "You cannot [not "should not"] be enslaved to God and Money."
The meaning.
The slave of God. Slavery to God is crucial for life in the kingdom. God's slave is free from anxiety (vv. 25-34), and thus - at last - able to affirm the whole of life ("Behold the fowls of the air," v. 26, "Consider the lilies of the field," v. 28, KJV). Only God's slave can do so. The one whose heart is set supremely on God and on heaven, is the one - the only one - in a position really to enjoy the things of earth. He or she receives them as a gift from the hand of a loving and provident Father. Jesus declares in 6:33, "Seek first his kingdom and his righteousness, and all these things [food, drink, clothing - the very things the pagans run after, 6:31-32] will be given to you as well." Cf. C. S. Lewis, "First and Second Things," God in the Dock, 278-81.
The slave of Money. On the other hand, blindness to the kingdom's coming makes one a slave of money. No wonder he "stores up for himself treasures on earth." He thinks this is the only place to do so! Tragically, his failure to acknowledge God, prevents his really understanding or enjoying the present order - he is blind to the eternal order and therefore to the temporal order. His position is the very opposite of that described under a. Slavery to Money ironically prevents the slave from enjoying things (both that Money can and cannot buy). He is perpetually anxious.
VII. LIVING WITHOUT ANXIETY. 6:25-34.
The Theological Foundation.
As noted, this section begins with "Therefore," 6:25a. The final section of the chapter rests upon what goes before - not just v. 24, but all that Jesus has taught in 6:1-24 (to go no further back). 6:25-34 sets forth some of the practical and psychological effects of the mentality and the faith called for in 6:1-24.
The Effects of Slavery.
The slave of God (6:24) has a singular objective - to do the Master's bidding. It is the Master's responsibility, not the slave's, to provide food, clothing, shelter, and protection. In the language of 6:33, "Seek first his kingdom and his righteousness [one way of expressing undivided loyalty and obedience to the Master], and all these things will be given to you as well."
The Effects of Prayer.
6:25-34 is to be viewed in light of the Lord's Prayer. With 6:10, cf. 6:33. He who offers the petition "Give us today our daily bread" in true faith (cf. 6:30b, "O you of little faith"), is the one with most reason to be free from anxiety - for he has cast his care upon a Father who is both able (because he is sovereign) and willing (because he is loving) to provide for the needs of his children and his slaves (cf. Phil 4:6-7).