Noticing how very different the actual facts which we know directly are from any of the material worlds by which we explain them, each of which lays claim to being “the reality with which sensible perception acquaints us,” some philosophers have put forward the view that in sensible perception we become acquainted, not with matter itself, but with signs which stand for a material world which exists altogether outside perception. This view Bergson rejects. He says that in sensible perception we are not acquainted with mere signs but, in so far as there is any matter at all, what we know in sensible perception is that matter itself. The facts which we know directly are matter itself and would be nothing but matter if they were instantaneous. For Bergson, however, an instantaneous fact is out of the question: every fact contains more than the mere matter presented at the moment of perception. Facts are distinguished from matter by lasting through a period of duration, this is what makes the difference between the actual fact and any of the material worlds in terms of which we describe them: matter, is, as we have said, only an abstraction of one element or tendency in the changing fact which is the sole reality: memory is the complementary abstraction. Apart from the actual fact neither matter nor memory have independent existence. This is where Berg-son disagrees with the philosophers who regard the facts as signs of an independent material world, or as phenomena which misrepresent some “thing” in “itself” which is what _really_ exists but which is not known directly but only inferred from the phenomena. For Bergson it is the fact directly known that _really_ exists, and matter and memory, solid tables, green grass, electrons, forces, the absolute, and all the other abstract ideas by which we explain it are misrepresentations of it, not it of them.