When Milton says, "the childhood shows the man, as the morning shows the day," he is referring to how children are wonderful teachers and how adults should learn from them rather than simply trying to instruct. The morning is the time when night ends and light blankets the world. The morning, then, is a revealing time. Children bring this same kind of enlightenment, although in a more symbolic sense.

The lines just before this quote are directed at a child who has snuck away from home to a religious temple where theologians are arguing. The child doesn't learn from these men, though they would be thought of as religious teachers—instead, he shows them the way to the knowledge they seek: "teaching, not taught."