He thought the scale had universal application or substantially the same in kind, with deviations from uniformity ... produced by special causes.

The prime analogate is an individual working his way up in society; that is, Morgan, who was well read in classics, relies on the Roman cursus honorum, rising through the ranks, which became the basis of the English ideas of career and working your way up, to which he blends in the rationalist idea of a scala, or ladder, of life.

Morgan rejects the Ages of Stone, of Bronze, of Iron, the Three-Age System of pre-history, as being insufficient characterizations of progress.

Worsaae had built his work on the foundation of evidence-based chronology by Christian Jürgensen Thomsen, whose Guideline to Scandinavian Antiquity (Ledetraad til Nordisk Oldkyndighed) (1836), was not published in English until 1848.

[4] Morgan believed the prehistoric stages as defined by the Danish were difficult to distinguish, as they overlapped and refer only to material types of implements or tools.

In addition, Morgan thought they did not fit the evidence he was finding among Native American societies in North America, in which he had closely studied social structure as an indicator of stages of civilization.

Based on the lines of progress, he distinguishes ethnical periods, which each have a distinct culture and a particular mode of life and do not overlap in a region.

A. Worsaae are credited with the foundation of scientific archaeology, as they worked to have controlled excavations in which artifacts could be evaluated by which were found together: the beginning of stratigraphy.

John Wesley Powell credited Ancient Society as "the most noteworthy attempt hitherto made to distinguish and define culture-stages".

Powell opposed the survival of the fittest theory because in his mind, humans did not advance their living conditions to succeed in the struggle for existence.