The third decan of Cancer covers 20° to 30° of the sign. A decan is a ten-degree third of a sign. Firmicus Maternus gives its face ruler, the planet of that slice in the Chaldean order, as the Moon. The Moon is also Cancer's domicile lord, the planet that rules the sign. Chaldean order deals out the seven visible planets from slowest to fastest, Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, three decans to each sign. Firmicus holds that a planet in its own decan acts as if in its own domicile. Medieval authors rank the face as the weakest of the five dignities. Here the face and sign rulers are the same planet, so a placement in this decan has the Moon in both roles. Cancer is a feminine, cardinal water sign. Later practice reads it as a lesser factor, after the planet's major dignities.