This paper considers the cultural significance of C.G. Jung's concept of synchronicity, as this was envisaged both by Jung himself and by the physicist Wolfgang Pauli, Jung's most important discussant in developing the concept. For both thinkers the principle of synchronicity was, above all, an attempt to develop an expanded, more holistic understanding of science. The paper argues, however, that their motives for proposing this development were not just, as might be expected, scientific, philosophical, and psychological (including personal), but also historical, social, political, and religious, and involved consideration of esoteric as well as mainstream currents of thought.