Man is constantly being provided with the provisions for his life by God. In fact, the whole earth has become a table laid with provisions for man. But the demand made by the believers in Jesus for food to be sent down from the sky caused a severe warning to be given to them. The reason for this is that the provisions we receive under normal conditions are routed through a veil of cause and effect, while the demand of the believers involved the removal of that veil. This is again the way of God, because if this veil is removed, the very purpose of test will be defeated.