Synthesized answer
The provided passages do not explicitly state the central thesis of "Einführung in das mathematische Denken" [1].
The title of the book, "Einführung in das mathematische Denken : Die Begriffsbildung der modernen Mathematik" by Friedrich Waismann and Karl Menger, suggests that the text aims to introduce mathematical thinking and specifically focus on the formation of concepts in modern mathematics [1]. However, this information alone does not detail the central argument or thesis the authors wish to convey.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Einführung in das mathematische Denken : Die Begriffsbildung der modernen Mathematik by Friedrich Waismann, Karl Menger Pages: 168