I have been assigned a subject that gives considerable latitude for interpretation. I propose to survey the broad outlines of biogeography from several different aspects. First I will discuss the scope of biogeography, in its two dimensions–almost necessarily seen as perspectives–looking outward into the world and looking backward into time. This will lead into a review of some of the principles and processes that underlie biogeographic phenomena. The two dimensions must again be considered, and we will mention both the reasons for present distributions and the not always identical reasons for distributions in the past. Then we will broaden the horizon to consider the relationship between biogeography and certain other branches of science. Finally I will try to look a little way forward and to hint at the biogeography of the future and what biogeography may be expected to tell us about the future. This is a large program for a short essay, and the treatment of individual topics must necessarily be brief and simplified.