So they asked him, "What miraculous sign then will you give that we may see it and believe you? What will you do? Our forefathers ate the manna in the desert; as it is written: 'He gave them bread from heaven to eat' "
Here is their objection to the feeding of the 5000. They'd seen it all before. Moses had fed them with 'magic' bread, not just once but for 40 years. They were determined not to be impressed by Jesus even though Moses was 1200 years in their past. They were as oppressed as a nation by the Romans as the Hebrews had been by the Egyptians and they were looking for a similar solution, but they failed to see Moses as a 'type' of Christ. They were looking for a savior who was a 'type' of Moses.