Four Cardinal Virtues
The reason there are six cards in the index at the bottom of this page rather than four is due to a discrepency in how the Virtue of Prudence is applied to a Trump that does not bear that name.
Eliphas Levi originally attributed Prudence to the Hermit card. However, I’ve also seen compelling arguments for using the High Priestess. The Hermit does have a lot in common with another small card called Prudence, the 8 of Disks ︎︎︎, whose formula is Sol in Virgo (the Sign attributed to the Hermit). However, the depictions of the Virtue Prudence are typically holding a Book, or Scroll, or a Mirror. The High Priestess almost always has either a Scroll or Book, and its correspondence is to the Moon, linked to Mirrors.
One final option could be the World, or Universe card. The final attribute common with depictions of Prudence is her gripping a serpent.
Below are four depictions of the Virtues from the Tomb of Pope Clement II (died 1047), in the Bamberg Cathedral.
It’s interesting to note Prudence’s detail in the above Mantegna deck, having an old bearded man on the back of her head. This may allude to the old man of the Hermit card, also relating to the Virgin through its correspondence to Virgo. There also happens to be a Snake in the Thoth Deck’s Hermit card. In the Wirth Tarot deck, the Hermit also has a Snake near his staff ︎︎︎. There are a few examples of Prudence being depicted with an old man on the back of her head:
Below are the four Cardinal Virtues from Giotto’s large collection of Vices and Virtues (1306):
In Giotto’s examples, Prudence has the most obvious link to the High Priestess.