A system and method for arranging concept clusters in thematic relationship in a two-dimensional visual display space is described. A plurality of stored clusters are selected from a multi-dimensional visualization space sharing a common theme including at least one concept. Each theme logically represents one or more concepts based on terms extracted from a document set. Each cluster not yet grouped from the selected clusters for the shared common theme is combined in order into a list of placeable clusters. Each clusters list is grafted into a grouping of one or more other clusters lists at an anchor point. The anchor point includes an open edge formed along a vector defined from the center of one such cluster in the grouping. The clusters in each other clusters list share at least one concept represented in the shared common theme.