A methodological general principle emerges from these considerations. Morphological characteristics of a species may be understood as a specialized form of the general (abstracted) type characteristic of the genus; each genus represents a special modification from the general structural pattern of the superordinate family; each family represents special deviations from the more general structural pattern of the order, etc. On the other hand, the systematic of behavior do not have the same hierarchical relationships. Discontinuities and unique traits are common; specializations of behavior seem to deviate more markedly from general patterns, and in many cases the specializations are so pronounced that the abstraction of general behavior types is impossible or hazardous.
基於這些考量，我們有了一個方法論上的一般原則。某一物種的形態特徵可以看作是所屬的屬的一般(抽象)特徵的一種特化的形式；一個科之下的每一個屬表現了對該科的一般結構樣式的一種特別調整；一個目之下的每一個科代表了對該目的一般結構樣式特殊的偏離。另一方面，行為的系統並沒有相同的階層關係。不連續的情形和獨有的特徵是常有的事；行為的特化似乎更顯著地偏離了一般樣式，而且在許多情形下，這些特化是如此的顯著以至於要對抽象出一般行為類型是不可能或是冒險的。
This difference in structural as opposed to behavioral systematics may be entirely due to the limitations of human observation and insight. We can discern, visually, the relationship between forms; but the relationship of behavior escapes our powers of observation more easily. However this may be, it leads to the following methodological principle:
結構的分類學相對於行為的分類學之間的差異可能完全是因為人類觀察以及眼光有侷限。我們可以從外觀上察覺形式之間的關係，但是行為之間的關係並不容易看得出來。然而，無論如何，這引出了以下的方法論原則。
Knowledge of structure alone cannot lead to exact inference of behavior patterns (only general modes of life); but once behavior patterns are known, we can understand and explain by hindsight certain specialization of morphology.
僅憑著對於結構的認識並不能使我們確切的推論行為的型態(只能推論生命的一般模式)；但是一旦認識到行為的型態，我們就能夠經由後見之明來了解並且解釋某些形態上的特化。
This is a methodological formulation. It does not give clues to the direction of causality; it does not assert that behavior is prior to form or vice versa.
這是一個方法論上的構想，它並沒有給我們線索去探討因果關係；這個構想並不主張行為先於形式，或者是形式先於行為。
