Monopsychism is the belief that all humans share one and the same eternal consciousness, soul, mind or intellect. It is a recurring theme in many mystical traditions.
Monopsychism is a doctrine of Sabianism, Jewish Kabbalah, and Averroism, and is also a part of Rastafarian beliefs. A similar belief in some mystical Jewish and Christian traditions is that all human beings have different souls but once composed a single unified soul in Adam. Thomas Aquinas disagreed with this belief and devoted most of his writing about Averroism to criticizing monopsychism.