The four virtues of classical philosophy as codified by Cicero are Prudence, Justice, Fortitude, and Temperance, originating with Plato and later adapted into the seven theological virtues of the Christian faith with the inclusion of “faith, hope, and charity (love).”  While Justice and Temperance jump out at one immediately as trumps in the Tarot, and recognition of the Strength card’s earlier designation as Fortitude fills in another gap, Prudence is left largely unaddressed. It seems impossible that only three of the four made it into the deck, so where is Prudence?
We have a few options:
- The card never existed.
- The card existed but was lost/removed at some point in history.
- The exists as a differently named variant, much like the Strength card.
I suggest that the first option is least likely, as the inclusion of the other three show a pattern of interest in the classical virtues being part of the trump series. It’s also the least interesting to consider, since if one accepts this proposal the remainder of the discussion becomes moot!
It is entirely possible that the card existed at some point but was subsequently redacted – omitted in error at some point along the way and lost to history. If so, until we recover the lost card, we must consider that it was either replaced by another card or represents a twenty-third card in the deck – and wouldn’t that prove meddlesome for their Kabbalistic associations! This once more proves a dead-end unless we are willing to manufacture a card of our own imagining.
Lastly, we may consider that the card was – like Strength (Fortitude) – renamed. If so, then how do we identify it? Fortunately, we do have some help in this. The three known cards associated with the Virtues all adhere to the standard classical representations of their related idea. The classical representation of Strength/Fortitude is often shown as a figure with a lion, that of Justice with scales and a sword, and that of Temperance with two jars, one of water and one of wine. These all align with the traditional images of the cards in the Tarot. Thus, we might look to the classical representation of Prudence to guide us, shown as a figure with a book, scroll, and/or mirror. It is also interesting to note that these images were always female, which is traditionally so for Strength/Fortitude, and arguably so for Temperance, with the evolving image of Justice being masculine explained by simple male-dominated cultural influence. The idea of “lady justice” – as shown with her representation in the Statue of Liberty – comes quickly to mind, as well, so we can interpret this card as feminine. 
This leaves us looking for a feminine card, or one that could be supported as such, among the cards that has a book, scroll, and/or mirror. One that fits this description is The High Priestess: a woman seated on a throne with a scroll or book in her hands. That’s a great start, but hardly definitive proof. What else can we use to determine the missing Prudence?
In observing the cards as they fall into place through the numbered tarot, there is a pattern of a Virtue, two cards, then a Virtue. We have Strength (8), two cards (Hermit, Fortune), Justice (11), two cards (Hanged Man, Death), and Temperance (14). Thus, if we extend the pattern, we could consider two cards preceding (Lovers, Chariot) and The Hierophant (5), or the two cards following (Devil, Tower) and The Star/Firmament (17). The Hierophant seems a stretch as inherently masculine, while the image of The Star/Firmament is of course a female. However, her imagery does not match that of Prudence in any way, and is in fact closer to that of the already-identified Temperance.
Have we now struck out? Possibly, but there is another consideration. If we accept that The High Priestess – aka the Female Pope or Papess – does match the imagery of Prudence, then switching her position with The Hierophant (or Pope) would align her as Prudence in sequence with the remaining series. In other words, she would appear as Prudence, then two cards (Lovers, Chariot), then Justice (or Strength), and so on. Considering that they represent masculine and feminine aspects of the same faculty, we now have a female figure that matches the classical imagery of Prudence in a position leading the pattern of Virtues in the trumps. Improving this argument is that Cicero’s listing of the four Virtues is in order Prudence, Justice, Courage, and Temperance, which is exactly the order given in the Tarot trumps if one ignores Mather’s inversion of Strength/Justice.
Now, those of you who study Tarot and its (albeit manufactured) attributions will revolt at this thought, as it implies that The High Priestess must be associated with the astrological sign of Taurus in order to maintain the sequence of the Zodiac beginning with Aries in The Emperor (4). This further means that The Hierophant must be associated with the moon, and while one could argue that the Isis-Bull-Taurus association is as good a fit as any for The High Priestess (Prudence), it is more of an intellectual leap to associate The Hierophant with the moon.
So, have we found Prudence? I think so, at least for the moment, embodied by The High Priestess whose title could have been modified in the time period in which these decks first appeared given the emergence and popularity of the “Pope Joan” legend at that time. A greater problem lies in accepting the re-ordering of the cards and its impact on their current astrological, planetary and elemental attributions, a consensus on which I suspect would not be soon forthcoming even were the evidence more concrete. (Tradition, after all, holds strong to the guise of accepted fact.) However, I think there is sufficient evidence for further consideration, and something I hope to look into further.
Dear Prudence, won’t you come out to play? – The Beatles
 I find it interesting that the later virtues of faith, hope, and charity do not appear at Tarot trumps, given the known history of the emergence of the Tarot in Renaissance Europe. No, the Tarot is not Egyptian, which is a fanciful attribution carried forward through the early 1900s. This arises from Court de Gebelin’s claim, but I strongly suspect he was saying such as a blind for the trumps’ association with Alchemy, or “al khemia” – meaning “from Khem (Egypt).”
 Aleister Crowley’s Thoth Tarot further identifies this card with the female Egyptian goddess Maat. So, in short, the figure represented in Justice is female, despite what your deck might show to the contrary – e.g. Rider-Waite.
 Mather’s reversal of Strength and Justice is of no concern here, as they are both Virtues and would affect the order, but not the pattern.
 The Star/Firmament can be seen as once again separating the liquids combined by Temperance, in fact. It is thus an alchemical image of distillation – some liquid returning and other liquid discarded. The earlier Visconti/Sforza decks do not bear out this imagery, however, merely showing a woman holding a star.