Carl Gustav Jung (1875–1961) introduced the concept of archetypes—universal, recurring images of the collective unconscious—independently of Tarot, within his own analytical psychology of the 1910s–1930s. He mentioned Tarot only occasionally, in private seminars (notably in his 1930s Visions Seminar notes), suggesting that the card sequence might intuitively mirror archetypal stages of personal development, but he never developed a systematic theory of Tarot and did not treat the deck as a therapeutic tool in the modern sense.

It was Jung's followers—notably the psychotherapist and Tarot researcher Sallie Nichols, and later more popular authors such as Eden Gray and Rachel Pollack—who, across the 1960s–1980s, systematically applied Jungian vocabulary to the cards, proposing to read the Magician, the Priestess, the Empress, and others as images of the Self, the Anima, the Shadow, and so on. This is a fruitful psychological reading, but it must be distinguished from the historical origin of the images, which, as earlier chapters show, lies in Renaissance allegory rather than twentieth-century psychology.

The idea of reading the 22 trumps as a sequential narrative of spiritual development—the 'Fool's Journey' from innocence through trials to wholeness—does not appear in any source before the twentieth century. The term and a developed methodology were popularized by the American Tarot teacher Eden Gray in her books of the 1960s–1970s (The Tarot Revealed, 1960; A Complete Guide to the Tarot, 1970), and the framework was then entrenched by numerous late-century instructional authors.

The model is pedagogically convenient: it gives a beginning reader a memorable frame for the 22 cards and structures learning. But it is superimposed on the deck after the fact—no Florentine, Milanese, or Marseille source describes a fixed 'journey plot' for the trump sequence, and card order itself (for instance, the placement of Strength and Justice) was not even uniform across regional traditions before the printed standards of the nineteenth and twentieth centuries.

Tarot historians (notably Helen Farley in A Cultural History of Tarot, 2009) treat the Fool's Journey as a telling example of how modern practice retrofits a narrative structure onto a deck whose historical makers required no such structure in this form.

In the second half of the twentieth century, psychologists and art therapists (including followers of Jung's 'amplification' method and later humanistic psychologists) began using Tarot's ambiguous imagery as a projective stimulus: like the Rorschach or TAT tests, a card with an open narrative scene prompts a person to project their own associations and articulate what was otherwise hard to name directly. This does not demonstrate any predictive power in the cards, but it explains their durable usefulness in conversational and reflective practice.

From the 1980s, authors such as Mary K. Greer (Tarot for Your Self, 1984) and Rachel Pollack (Seventy-Eight Degrees of Wisdom, 1980–1983) established a 'psychological' Tarot as a distinct strand, separate from predictive divination and closer to tools of self-reflection and coaching. It is worth stressing a methodological boundary here: academic psychology does not recognize Tarot as a diagnostic or therapeutic instrument with demonstrated efficacy; its value in this context lies in structured reflection, not objective knowledge of the future or the psyche.