Playing cards arrived in Europe in the fourteenth century, most likely via traders from the Islamic world, where the Mamluk deck already grouped cards into four suits: cups, coins, swords, and polo sticks. These were functional categories, reflecting the world of the court and the military. But when cards spread into Europe, something interesting happened. Different cultures translated the suits through their own social lenses, and the suits began to carry meaning. In fifteenth-century Germany, the suits became hearts, bells, leaves, and acorns, imagery drawn from rural and hunting culture. More significantly, they mapped loosely onto the four estates of medieval society: the clergy, the nobility, merchants, and peasants. The deck became a miniature model of the social world, each suit representing a different way of moving through life. The French rationalised these suits into the shapes we use today: hearts, diamonds, spades, and clubs, largely for ease of printing. But the social symbolism carried over. Hearts represented the church and the spiritual domain. Diamonds mapped to the merchant class and the world of commerce. Spades, derived from the word for sword or pike, stood for the military nobility. Clubs, originally a clover or trefoil, came to be associated with the peasantry and the rough wooden cudgel of the common labourer. This was not merely decorative. The French were mapping out what they understood to be the fundamental categories of human society: those who pray, those who fight, those who trade, and those who work the land. Four modes of being, four ways of contributing to the whole. By the time the deck reached England, much of this intentional symbolism had dissolved. The suits became conventional, their meaning forgotten. But in other traditions, particularly in tarot and the esoteric currents of the sixteenth to nineteenth centuries, the suits continued to be read as the four elements, the four temperaments, the four fundamental patterns of human character. The idea that four distinct categories can capture something essential about how people differ is, it turns out, a very old one. Where StrongSuits picks up the threadStrongSuits did not set out to revive medieval estate theory. But when its creator, Dave Corbet, came to design the four suits of the StrongSuits deck, he was drawing on research traditions that arrived at a strikingly similar conclusion: that human beings cluster into four recognisable patterns of interaction, and that understanding this makes it possible to build better teams. The most direct influence is the work of William Moulton Marston, whose 1928 book Emotions of Normal People proposed four behavioural patterns based on two distinctions: whether a person tends toward active or passive engagement, and whether they perceive their environment as broadly favourable or unfavourable. From these two axes, Marston derived four patterns: Dominance, Inducement, Submission, and Compliance. This became the theoretical foundation for what we now know as the DISC model, one of the most widely used behavioural frameworks in organisational life. Linda Berens developed Marston’s thinking further, focusing specifically on how people interact with others rather than on underlying personality traits. She identified four interaction styles. Some people prefer to have a plan and know what is going to happen before they act. Others want to focus on results and simply get things done. Others again prefer to get along, taking time to integrate different perspectives before moving forward. And others lead with inspiration, wanting to energise and persuade those around them. These four interaction styles map directly onto the four suits in StrongSuits: Spades for drive and getting things done, Clubs for relationship-building and integration, Hearts for passion and inspiration, Diamonds for precision and upholding standards. The suits are not arbitrary. Each one represents a coherent cluster of strengths that belongs to a recognisable way of showing up in the world. Understanding these differences matters because of what happens when people do not feel safe to show them. When Google launched its internal Project Aristotle research in 2012, studying more than 180 teams to find out what made the best ones effective, the result was not what anyone expected. Individual talent, team composition, and collective expertise all mattered less than one thing: whether people felt safe to speak up, share mistakes, and bring their real perspectives to the work. This built directly on the research of Harvard Business School professor Amy Edmondson, who had been studying team psychological safety since the late 1990s and whose framework underpinned Google’s findings. For many HR professionals and coaches, this is now familiar ground. What StrongSuits offers is a practical way into it: a structured, low-threat starting point for the kind of honest conversation about strengths and working styles that psychological safety requires but that rarely just happens on its own. Strengths as the Unit of CurrencyOnce the four suits were established, the task was to identify the thirteen strengths that belong to each one. This was not a casual process. The development of the StrongSuits deck drew on a wide range of workplace competency frameworks: the University of California core competency model, the UK Civil Service competency framework, Harvard University’s competency dictionary, and research published in the Harvard Business Review by Zenger and Folkman, among others. A long list of over a hundred positive workplace qualities was assembled and then refined, with thirteen strengths selected for each suit. | 
