Taxonomy is static, its symbols are therefore two-dimensional, representing 1. differences or resemblances and 2. diversity (eventually are also area). Phylogeny is dynamic and its symbols are three-dimensional, representing 1. Time, 2. differences or resemblances and 3. diversity (eventually also migration). The term ”genorheithrum“ is proposed for a ”stream of potentialities“ as a phylogenetic unit in the Time. Taxonomic units are cross-sections through genorheithra, the boundaries of which are discontinuities of various kinds. A new discontinuity originates, as a rule, from a great number of potentialities (not from a single [pair of] parents). This implies the probability of polytopy as a common phenomenon, and also the supposition of a minimum of genetic property, below which a discontinuity is not viable. Natural extinction may be largely due to the loss of potentialities. — Corresponding reasonings may be applied to Biogeography, which may be static (floristics and faunistics) or dynamic (migrations). Taxonomic units are represented here by areas, the rate of extension of which may be a function of the number of potentialities. The forces, influencing the motion of any point of an area boundary are briefly summarized in a table, demonstrating tho embarrassing complexity of WILLIS’ statistical methods. In addition, the ”law of BEYERINCK“ is formulated anew on a broader basis. Disappearing of areas may be due to two causes: extinction of the units (loss of potentialities), or dissolution into new units (areas). The minimum of potentialities mentioned finds a geographic analogon in the law of the minimum area, established by PALMGREN.