1. Open up any Wikipedia site.
  2. Click on the first link that appears outside of parentheses in the main text of the article.
  3. Continue clicking the first link in each successive article.
  4. Eventually, you will reach the entry for “Philosophy.”
  5. Click on the first link in the “Philosophy” article, and you are taken to “existence.” Click on the first link there and you return to “Philosophy,” thus entering an infinite recursive loop.

There are more things in heaven and earth, Horatio, / Than are dreamt of in your philosophy.

An explanation of the phenomenon.