Having children is a great way of making labourers for the fields without actually paying them. Children both had a great value and little value, depending on how useful they were. If you even had a child for long in the first place. The level of deaths among infants in the past, both far and...
Think of our real life moon's very real and powerful effect on the Earth. It brings tides in the sea. Much like the moon, tides are predictable. It also moves towards or away from us in a predictable fashion. People deriving magic from a moon would likely have its effects very well predicted...