Starting with the names Cain and Abel — two brothers — we find that they are remarkably similar to the English words can and able, which are synonyms. Abel is both an anagram and a homophone of able, while Cain is a near-homophone of can and an anagram of “I can.”
Abel’s name in the original Hebrew is Hebhel, but the initial ‘h’ has been lost in English. The English word able comes, by way of French, from the Latin habilis, the initial ‘h’ also having been lost.
The Latin for “I can” or “I am able” is possum. Obama used the first-person plural version of the same verb on his 2008 campaign logo, a version of the presidential seal with “Vero Possumus” in the place of “E Pluribus Unum.” This was meant to be a Latin translation of “Yes, we can” — though one might be forgiven for misreading it as “really a possum.” The presence of letter “o” right before “possumus,” and the big O-for-Obama at the center of the seal, makes the possum/opossum connection even more natural.
Opossum, according to the Oxford English Dictionary, is derived from an Algonquian word literally meaning “white dog.” Translating back into Latin, that gives us canis albus — remarkably similar to Cain/Abel and can/able. (In fact, abel, an Old French word for the white poplar, is derived from albus.)
Dogs figure prominently in Jewish legends about Cain and Abel. Abel’s body lay unburied for some time (since no one had any experience of death or knew how to deal with it), and his faithful dog stood guard and protected it from wild animals. God also gave Cain a canine companion to protect him from any wild animals who might try to avenge Abel. (It’s not clear if this was a different dog, or if Cain inherited his brother’s pet.) No mention is made of the color of the dog. However, legend has it that to mark Cain as a sinner God afflicted him with leprosy, which would have made his skin unnaturally white (as in Ex. 4:6, “leprous as snow”), so the dog + white pattern is still there.
The white dog also appears on Fool card in the Rider-Waite-Smith tarot.
The fool himself is portrayed here as a wanderer with a knapsack, which fits with Cain’s fate as a “fugitive and a vagabond.” The fact that the fool is about to walk off a cliff, and seems quite unconcerned about it, also fits with the legends associated with Cain: that he was cursed to wander forever, that he often sought death but it was denied him. (The theme of not-really-dying brings us back to the possum, which is where this white dog stuff came from in the first place.) Traditional interpretations have the Fool card standing for beginnings, potential, possibilities — can and able.