58 Hence this whole precept is reduced to the following rule, that even in looking after such things we should think of the kingdom of God, but in the service of the kingdom of God we should not think of such things. For in this way, although they should sometimes be wanting (a thing which God often permits for the purpose of exercising us), they not only do not weaken our proposition, but even strengthen it, when it is examined and tested. For, says He, “we glory in tribulations also; knowing that tribulation works patience, and patience experience, and experience hope: And hope makes not ashamed, because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us.” Now, in the mention of his tribulations and labours, the same apostle mentions that he has had to endure not only prisons and shipwrecks and many such like annoyances, but also hunger and thirst, cold and nakedness. But when we read this, let us not imagine that the promises of God have wavered, so that the apostle suffered hunger and thirst and nakedness while seeking the kingdom and righteousness of God, although it is said to us, “Seek ye first the kingdom of God and His righteousness; and all these things shall be added unto you:” since that Physician to whom we have once for all entrusted ourselves wholly, and from whom we have the promise of life present and future, knows such things just as helps, when He sets them before us, when He takes them away, just as He judges it expedient for us; whom He rules and directs as parties who require both to be comforted and exercised in this life, and after this life to be established and confirmed in perpetual rest. For man also, when he frequently takes away the fodder from his beast of burden, is not depriving it of his care, but rather does what he is doing in the exercise of care.
Source: Our Lord's Sermon on the Mount (New Advent)