Model of the socalled "Ur-Tarot"
- Marseille-Type; also called Standard-Tarot)

the persons to the left - a dice-structure

the battlefield in the middle - a life-tree-structure

the lights to the right - a dice-structure

0 Fool

1 Magician

2 Popess

3 Empress

4 Emperor

5 Pope

6 Love	7 Chariot	8 Justice
9 Hermit	10 Wheel	11 Strength
12 Hanged Man	13 Death	14 Temperance
	15 Devil

16 Turm

17 Star

18 Moon

19 Sun

20 Judgment

21 World

Notes:

Left and right two dice or cube structures. Top and bottom should be 0/1 and 20/21, East-West-South-North unites the units 2-5 and 16-19. Perhaps somebody has difficulties to recognize Tower as a light. "Sagitta", the old Italian term, means a "lightning". The two dices (or cubes) at begin and end of the structure mirror each other.
In the middle 6-15 is a life-tree structure. The scheme is builded according to the row of the numbers.
At the top-row (Love - Chariot - Justice) we've good, positive elements, at the bottom row we've bad, negative elements : Hanging Man, meaning "traitor", and Death and Temperance. Temperance is the virtue of body and body is "negative" against spirit. Spirit should've been presented by Prudentia in the top row, but it isn't, instead there is Iustitia, a "very special riddle" in the deck and it will be solved below. The middle row presents soul and the change of life: Hermit (= time) , the Wheel of Fortune, which in this position is in the center of a wheel (builded by 6-7-8-11-14-13-12-9,) and Strength-Fortitudo as the virtue of soul.
In the left colum Love has its counterpart as treachery, balanced in the middle by time (Hermit). In the middle column meets the Triumph its Death, in the middle the destiny rules about reigning and losing. The left column is filled with 3 cardinal virtues.
The Devil is the terminating 10th element in the life tree structure - of course, this is a little strange.
I doubt, that it was from begin on a "Devil", I'ld assume, that this position was filled in the mind of the constructor of the scheme with the Visconti-Snake, the known and proud heraldic device of the Visconti. This card has survived twice in the fragments of the Visconti decks, a devil was missing. Actually there is no reason recognizable, why the Sforza on their proud Trionfi deck should've placed the devil on this central position of the whole structure.
Later, probably by foes of the Visconti-Sforza, the card of the heraldic device was exchanged, probably to express an humilation of the earlier rulers of Milan. As historical time for this action of humilation the years after 1500 are likely, when the Sforzas were dethroned for the time being.
To our knowledge of the moment the years 1505 shows the birth of the word Taraux or Tarrocco, it appears in France and in Ferrara, Italy, at nearly the same time (France and Ferrara were allied then). This indicates a mass production from the French side, taking the Milanese motif, but humilating the earlier reignment of Milan by replacing the heraldic design to the degrading figure of devil.
The heraldic device of Milan shows a snake or dragon with a human in its mouth. As far we do know the early devils of Tarot, which know not much examples, we do see a devil with a man in the mouth - as the Visconti-Snake. For the French card-makers it was an easy step to change the deck from snake to devil.
The virtue Prudentia was missing in the socalled Standard Tarot and this fact did lead to a lot of confusion about the real content of Tarot. However, when we replace the devil with the Visconti-snake then we can recognize, that in the iconography of Prudentia the virtue often was accompanied by a snake, presenting wisdom.
A likely date for the origin for the first Visconti-Sforza deck with 22 trumps is the year 1468. The young duke Galeazzo Maria married Bona of Savoia, and marriages traditionally were good opportunities to create new playing card decks. At such opportunities it was surely not custom to present the devil at a central position inside a card deck, but obviously it was an opportunity to present an important symbol of the family at such a position. The symbol chosen, the Visconti-Snake naturally offered to associate it too Prudentia. As already noted above, the "logical" position inside the shown scheme would have been position 8, the place of Iustitia, but, as it seems, the order was changed according to this game of heraldic, and Prudentia alias Visconti-Snake got the centralised position 15.

So let's correct it: Kick the devil out, replace it with some Prudentia. Matters look a little different then.

We've then something, that is a little more real the true "Ur-Tarot" - not really, as there had been other things before. But good enough to counter this talking of "Ur-Tarot" and this wrong approach of historical research of an object with many faces.