It is the distinction of the Greeks alone among the nations of antiquity that they practised a system of medicine based not on theory but on observation accumulated systematically as time went on. The claim can be made for the Greeks that some at least among them were deflected by no theory, were deceived by no theurgy, were hampered by no tradition in their search for the facts of disease and in their attempts at interpreting its phenomena. Only the Greeks among the ancients could look on their healers as _physicians_ (= naturalists, φυσις {physis} = nature), and that word itself stands as a lasting reminder of their achievement.[56] [56] The word φυσικος {physikos}, though it passed over into Latin (Cicero) with the meaning _naturalist_, acquired the connotation of _sorcerer_ among the later Greek writers. Perhaps the word _physicianus_ was introduced to make a distinction from the charm-mongering _physicus_. In later Latin _physicus_ and _medicus_ are almost always interchangeable. At a certain stage in the history of the Western world--the exact point in time may be disputed but the event is admitted by all--men turned to explore the treasures of the ancient wisdom and the whole mass of Greek medical learning was gradually laid before the student. That mass contained much dross, material that survived from early as from late Greek times which was hardly, if at all, superior to the debased compositions that circulated in the name of medicine in the middle centuries. But the recovered Greek medical writings also contained some material of the purest and most scientific type, and that material and the spirit in which it was written, form the debt of modern medicine to antiquity.