Without this playing with fantasy no creative work has ever yet come to birth. The debt we owe to the play of imagination is incalculable.

Jung is arguing that imagination—specifically the free, “playful” movement of fantasy images—is not a frivolous escape from reality but a generative psychological function. In his view, creativity in art, thought, and even scientific insight depends on allowing unconscious material to surface in symbolic form before it can be shaped into a finished work. The line also reflects Jung’s broader emphasis on the psyche’s self-regulating, meaning-making capacities: fantasy provides raw material through which individuals and cultures discover new possibilities, compensate one-sided rationalism, and renew themselves. The “incalculable” debt underscores how foundational this imaginative play is to human culture.