Whittaker, following Siebeck, pointed out the important role Plotinus assigns to the functions of imagination in psychic life. Imagination is the terminus ad quern of all properly human conscious experience; it is that faculty of man without which there can be no conscious experience. The sensitive soul is an imaginative soul below which there is Nature, or vegetative soul, which acts without being conscious. When the functions of reason are added to sensation to produce a rational human being, there is (...) conscious discursive thought as well as conscious sensation; and since the sensitive soul cannot be responsible for the imaging of rational concepts, Plotinus asserts the existence of a conceptual imagination. (shrink)