The pre-eminent or principal virtues on which all the others hinge or depend.
They are temperance, fortitude, prudence, and justice.
They are referred to in the ritual of the Entered Apprentice Degree, and will be found in this work under their respective heads. In the eighteenth century the Freemasons delineated the symbols of the four cardinal virtues by an acute angle variously disposed. Thus, suppose you face the east, the angle symbolizing temperance will point to the south. It was called a Guttural.
Fortitude was denoted by a saltire, or Saint Andrew's Cross, X. This was the Pectoral.
The symbol of prudence was an acute angle pointing toward the southeast, and was denominated a Manual; and justice had its angle toward the north, and was called a Pedestal or Pedal.
The possession of cardinal virtues is no special distinction of Freemasons, for other societies have had them. They are in evidence in the Christian church. The fifteen cardinal virtues, in mosaic, in the dome of Ascension of Saint Mark's at Venice is a famous example.
Source: Mackey's Encyclopedia of Freemasonry