An influential dogma in philosophy of mind and cognitive science is that consciousness studies originates in the seventeenth century with René Descartes. I aim to dispel this dogma by explaining Plotinus’ theory of consciousness. The key feature of his theory is that it involves multiple-layers of experience. Central to my argument is that each layer of consciousness has unique capacities, that the higher the layer the more unifying the capacity, and that the more unifying the capacity the closer together are thought and being. The turn inwards and ascent upwards culminates in the highest layer, which enables us to assimilate to the rationality of Intellect and the self-sufficiency of the One. Unity is the governing principle in Plotinus’ theory. The more unified we are, the less we are in need of being completed by things that are external to ourselves and beyond our control. This multi-layered model shows that in order to understand a conscious mental state, one has to understand the entire cognitive architecture of the mind, and one needs to take into account the lower levels of consciousness a conscious mental state is completing and the higher levels it is drawing on.