cardinal virtue

noun[in the plural]1

1. •
   One of the four foundational virtues identified by Greek and Christian philosophers, on which other virtues depend: justice, temperance, prudence, or fortitude.

   • Even the cardinal virtues cannot atone for half-cold entrées, as Lord Henry remarked once, in a discussion on the subject, and there is possibly a good deal to be said for his view. — 1891