Overview
Spengler's world-historical outlook is informed by many philosophers, Goethe and Nietzsche among them, and the former more than the latter. He would later further explain the significance of these two German philosophers and their influence on his worldview in his lecture Nietzsche and His Century . His analytical approach is that of "Analogy. By these means we are enabled to distinguish polarity and periodicity in the world."
Morphology is a key part of Spengler's philosophy of history, using a methodology which approached history and historical comparisons on the basis of civilizational forms and structure, without regard to function.
In a footnote, Spengler describes the essential core of his philosophical approach toward history, culture, and civilization:
Plato and Goethe stand for the philosophy of Becoming, Aristotle and Kant the philosophy of Being... Goethe's notes and verse.. must be regarded as the expression of a perfectly definite metaphysical doctrine. I would not have a single word changed of this: "The Godhead is effective in the living and not in the dead, in the becoming and the changing, not in the become and the set-fast; and therefore, similarly, the reason is concerned only to strive towards the divine through the becoming and the living, and the understanding only to make use of the become and the set-fast.(Letter to Eckermann)" This sentence comprises my entire philosophy.
Scholars now agree that the word "decline" more accurately renders the intended meaning of Spengler's original German word "Untergang" (often translated as the more emphatic "downfall"; "Unter" being "under" and "gang" being "going", it is also accurately rendered in English as the "going under" of the West). Spengler explained that he did not mean to describe a catastrophic occurrence, but rather a protracted fall—a twilight or sunset. (Sonnenuntergang is German for sunset, and Abendland, his word for the West, literally means the "evening land".) Writing in 1921 Spengler observed that he might have used in his title the word Vollendung (which means 'fulfillment' or 'consummation') and saved a great deal of misunderstanding. Nevertheless, "Untergang" can be interpreted in both ways, and after World War II, some critics and scholars chose to read it in the cataclysmic sense.
Read more about this topic: The Decline Of The West