The Moon, Selene… The satellite of our planet has always enlivened people’s imagination. The first day of the week, Monday is dedicated to her. She has been a Goddess in the classical civilizations, the tide gazers look at her to know the tides, and people of all cultures have used her as a measure of time. In the Middle Ages, it was believed that when night fell or there were eclipses, they had to help the moon to survive, making the greatest possible noise. The moon has always occupied a central place in the beliefs of the Peninsula, in the north, people believe to see on its surface an old woman spinning, or another who, surprised by the moon while stealing wood, was absorbed by it. In the Basque Country they believe that she is the daughter of the Earth, they call her grandmother and address her by that name.
It is believed that during the full moon a person, especially a child, can be caught by the moon, making him or her go crazy. For this it is not necessary to be out of the house; a flash of lightning penetrating through the window and hitting the sleeping person or the night light spilling on clothes lying on the floor is enough. And if eggs, meat or milk are left outside, they will almost entirely spoil. Nor can you slaughter when the moon is full.
As for the waxing and waning phases, they have always been taken into account for any activity to be carried out. For example, it was believed that to have a male child, the ideal date would be the waxing moon and for the opposite, the waning moon. Also when someone dies in the waxing moon is considered as a good omen. It is also believed that in the crescent quarter of any month, but never on Friday, hair and nails should be cut to make them grow stronger.
Sources:
Mercedes Cano Herrera. (2007). Entre anjanas y duendes : mitología tradicional ibérica. Castilla Ediciones.