The Previous Rebbe once told a story about his father’s first day in preschool [cheder]. The boy’s grandfather, the Tzemach Tzedek showered him with candies and told him they had been thrown by the angel Michael.
Those candies were so precious to the young Rashab that he didn’t eat them. Finally when the adults searched his room for chamatz before Pesach, they found the treats intact in his pocket. The Tzemach Tzedek told the boy, “Here are the candies; you should eat them.”
Our Rebbe explains that, in essence, the candies had been thrown by the angel Michael who recounts the merits of the Jewish people. The father and teacher are merely agents of that angel. Therefore when they throw those candies, they are serving as Michael’s representatives.
We tell this to a child rather than an adult, because an adult finds it difficult to accept the truth because, he “knows” where the candies came from using his intellect. A child doesn’t know where they came from, so he or she accepts the essential truth.