The modern deck of playing cards that we know today is intimately connected with the Tarot. There is much speculation as to whether playing cards developed from the Tarot or the other way around. They are certainly closely connected and at the very least have a common origin and that origin is an Indo-European one. The cards reflect Indo-European cosmic and spiritual themes and certainly the imagery of the older Tarot decks is indicative of this. (See Origins of the Tarot: Cosmic Evolution and the Priciples of Immortality, Dai Leon)
The Minor Arcana of 56 cards is divided into the 4 suits of wands, pentacles, cups and swords. Playing cards are 52 in number and also have 4 suits divided into clubs, diamonds, hearts and spades. Modern playing cards have 3 court cards: King, Queen and Jack. The alternative name for the Jack is Knave. The Tarot has all of these and a Knight as well. The Knave or Jack which would have ranked as a Squire, an attendant or an apprentice to a Knight who aspired to become one. Usually Squires were drawn from the lesser nobility and the rank still exists today in England. In fact the term of address Esquire as in John Smith, Esq has its origins in this rank and was traditionally used to denote men of higher social status, usually property owners. One still sees this as a courtesy title on envelopes and letters but I suppose that most younger people will not be familar with this.
Thus decks of playing cards have a direct association with the Minor Arcana which does cause us to speculate on the even more mysterious Major Arcana but this is a topic which I will reserve for another day. Everyone will be aware that the Tarot is used for purposes of divination but it is less commonly known that playing cards can also be used for this purpose too just as the Minor Arcana may be used as a playing deck. In the 1950s my mother (much to the displeasure of my father) would use standard playing cards for divination. She came from a family in the Harz mountains, the women in particular having certain psychic abilities. The Harz mountains was a well known centre of Germanic heathenism and what they would later term as 'witchcraft'.
Modern playing cards feature either 1 or 2 Jokers which may correspond to the Fool of the Major Arcana. Before the standardisation of the modern deck of playing cards different European countries had variations of the suits:
France: Hearts, Diamonds, Clubs and Spades.
Germany: Hearts, Bells, Acorns and Leaves.
German Switzerland: Roses, Bells, Acorns and Shields.
Italy and Spain: Cups, Coins, Clubs and Swords.
Minor Arcana: Cups, Pentacles/Coins/Rings/Discs, Wands/Clubs/Battons/Stavs and Swords.
One can see that there is considerable overlap between these various national suits and the Minor Arcana. There is clearly something significant about this recurring symbolism and in my opinion it is rooted in the 4 Hallows of the Tuatha De Danann:
Hearts/Roses/Cups = the Cauldron of the Dagda.
Diamonds/Bells/Coins/Pentacles = Lia Fail (Stone of Destiny).
Clubs/Acorns/Wands/Battons/Stavs =Spear of Lugh.
Spades/Leaves/Shields/Swords = Sword of Nuada.
My readers can see clearly the Tarot links with the Cauldron, Spear and Sword but the link between the Stone and Diamonds/Pentacles is not so clear but Arthur Edward Waite, the renowned scholar of the Tarot made this observation:
"The Wand is alternately a sceptre in the Tarot descriptions, but its proper alternative in the symbolism is a spear or lance, the misnamed Diamond in the modern suit being obviously the head of the weapon. In respect of the Pentacle that which is depicted under this name answers to a Dish, having usually the outline of a four-leaved shamrock." (The Holy Grail. History, Legend and Symbolism)
So there appears to be some overlap between the symbolism of suit of Clubs and the suit of Diamonds in respect of the Spear. Likewise an overlap exists between Hearts/Cups and Diamonds/Pentacles with the Cauldron. In the Parzival romance literature we find a close thematic relationship between the Spear and the Cup/Stone and likewise between the Cup and Stone. These symbols are inextricably linked to one another. In Arthurian literature of course we have an association between the Sword and the Stone. We also need to take into account that often in the Graal literature the Stone is substituted for a Dish and this distortion is evident in the Tarot. I am however reminded by something I have read in the rather remakable book Stonehenge of the Kings by Patrick Crampton:
"Tuatha De Danann had four talismans: the Great Fal-the stone penis of Ireland at Tara, which shrieked under the king of Ireland; the spear of Lug against which no victory could be won; the sword of King Nuada, which no one escaped when it was drawn from its scabbard; and the cauldron of the Dagda from which no one went away unsatisfied."
Of course Mr Crampton seems to take the view that the Stone of Tara is the Lia Fail which is conjecture. It would not be wise to consider that the 4 Hallows of Irish myth are necessarily physical objects. However when we consider the stone as being phallic in shape then this could be compared with the suit of Diamonds.