Why could Melchizedek's bread and wine point to Christ even though Abraham did not understand it?

Les explains that the king of Jerusalem brought forth bread and wine, which was unusual because bread and wine were not used in tabernacle worship or alluded to in the Old Testament economy. That imagery leaps ahead to Christ's death, burial, and resurrection, for the bread and wine spoke of His broken body and shed blood. Abraham likely had no concept of what Melchizedek was doing, but God did, because God knew the end from the beginning. Melchizedek was not a priest of Judaism, Moses, or Aaron, but a priest of the Most High God. That title points predominantly to the non-Jewish world, as when Nebuchadnezzar called Daniel's God the Most High. Melchizedek was not high priest of Israel, since Israel was not yet on the scene, but high priest of the whole human race and a picture of the priesthood Christ would fulfill. Thus the bread and wine could point forward even without Abraham's understanding.