The miracle of the feeding of the 5000 (in Luke 9:10 -17) is well known and demonstrates the authority of Jesus over the physical, but the real miracle was not the physical.
The people where not overly impressed by the feeding of 5000, because they remembered that God had fed the whole Hebrew people for 40 years in the desert (Manna and Quail, Exodus 16).
Jesus however came to feed a spiritual hunger, and the hunger he came to fulfil would be forever. By dying on the cross He would feed the spiritual needs for all people who turned to Him, they would be forgiven for the wrong things they had done (failing to be obedient to God =Sin) and would have a renewed relationship with God.
Jesus called this the Bread of life.
He called on His disciples (all who follow Him) to feed the people (all people) His Bread of life, to share the Good news so they may be spiritually replete.