Before doing so it is desirable to point out explicitly a distinction which, though obvious in itself, has apparently been overlooked or slurred over by some of Pausanias’s critics. The matter of his work is of two sorts, historical and descriptive: the one deals with events in the past, the other with things existing in the present. For his knowledge of past events, except in so far as they fell within his own lifetime and observation, Pausanias was necessarily dependent either on written documents or on oral testimony, in short on the evidence of others; no other source of information was open to him. For his knowledge of things existing in the present, on the other hand, he need not have been indebted to the evidence of others, he may have seen them for himself. It does not, of course, follow that what he may have seen he did actually see. His descriptions of places and things, like his narratives of events that happened before his time, may all have been taken from books or from the mouths of other people; only it is not, as in the case of the historical narratives, absolutely necessary that they should be so derived. This distinction is so elementary and obvious that to call attention to it may be deemed superfluous. Yet some of the critics appear to labour under an impression that, if they can show the historical parts of Pausanias’s work to have been taken from books, they have raised a presumption that the descriptive or topographical parts were also so taken. They do not, indeed, put so crass a misapprehension into words, but they seem to be influenced by it. To brush away these mental cobwebs it is only needful to realise clearly that, though Pausanias certainly could not have witnessed events which happened before he was born, he was not therefore necessarily debarred from seeing things which existed in his own lifetime. In investigating the sources of his information it is desirable to keep the historical and the descriptive parts of his work quite distinct from each other and to enquire into each of them separately. [Sidenote: Poets used by Pausanias.]