These verses essentially repeat the divine charge to the Twelve (and, by extension, at least in principle, to all of us) to avoid anxiety and undue worry about food and clothing and shelter. If the God of heaven chooses to feed the fowls of the air, if he provides means for the growth and beautification of grass and flowers on earth, then will he not help us provide for the crowning creature of his creative enterprise-man?.
Christ calls on us to focus on firts things, and then make proper efforts to provide for our needs. The message here follows on the heels of that which was just considered: one cannot have an eye single to the glory of God in the present if the spends every waking thought fretting about the future.