Friedrich Nietzsche? Apocryphal?

Question for Quote Investigator: A fatigued philosopher may forgetfully return to previous ideas. The worn out thinker may fruitlessly reexamine notions that were rightfully rejected in the past. The famous German philosopher Friedrich Nietzsche has received credit for the following remark:
When we are tired, we are attacked by ideas we conquered long ago.
I am skeptical of this ascription because I have not seen a solid citation. Also, I have not seen the original statement in German. Would you please explore this topic?
Reply from Quote Investigator: Friedrich Nietzsche died in 1900. The earliest evidence located by QI appeared many years later in the 1957 collection “The Book of Unusual Quotations” compiled by Rudolf Flesch which included the following entry. Emphasis added to excerpts by QI:1
When we are tired, we are attacked by ideas we conquered long ago.
FRIEDRICH NIETZSCHE
This article presents a snapshot of current research followed by a tentative conclusion. The German versions of this quotation seen by QI were apparently derived from the English statement, and QI has been unable to find earlier matches using German instances.
Below are additional selected citations in chronological order.
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