In the taijitu (the yin yang symbol) each half contains a dot of the opposite color. The idea is that anything in the extreme can become its opposite. There are different ways of reading the I Ching, the book of changes. Throwing three coins is the method I know best and have used the most. I’ll spare you all the details, but you use three coins to determine if a given “line” is yine or yang. Six throws, gives you six lines, and that in turn tells you which part of the book to read for your guidance. Using coins, heads mean yang and tails mean yin. If you get two of three coins showing one way or the other, that tells you the definition of the ‘line’ as either yin or yang. If you get all three coins the same it is considered a “changing line” which means it is SO yin or SO yang that it can easily tip over into being its opposite (or is in the process of doing so)
The Ten of Coins is a liminal symbol like a transition line. Coins (or Pentacles, depending on the deck you use) have to do with the physical realm, wealth, career, etc. 10 is the largest of the number cards before you move into the esoteric, idea-driven court cards. 10, in this case, is something coming to fruition or completion. It is the uber-pentacle of all the number cards. Given all of that, you might expect to see material successes represented, the Tarot equivalent of a mansion and a yacht.
The Ten of Pentacles is the happy family card. It shows simple contentment, in the RWS tradition usually mom, dad, their 2.2 kids, white picket fence, grampa and the dog. Granted, that sounds like a 1950s surburban ideal gone wild, but that’s kind of the point. The pinnacle of material success isn’t material at all. The pinnacle of material success is the people you love and simple contentment with the cycles and flows of life. Life, love and simple mindful pleasures are, after all, the greatest of treasures. All those little things are really kind of big.