My #2 was interestingly vague. The "Time" was no surprise -
   lifetime Doctor Who Fan, always been interested in time travel,
   the nature of time, etc... but the 2nd "most certain" AI tagged
   entry was a vague 120. So, I looked.

   Since 1979, 125 was removed:

   120 Epistemology, causation, humankind
   121 Epistemology (Theory of knowledge)
   122 Causation
   123 Determinism & indeterminism
   124 Teleology
   125 Not assigned or no longer used
   126 The self
   127 The unconscious & the subconscious
   128 Humankind
   129 Origin & destiny of individual souls

   So what was it? The 1971 DDC 18 gave a clue. Yeah, I'm a nerd.

   I found out. Does it mean anything? I dunno. But that's why I'm
   investigating. Might as well; I'll never be famous enough for
   _someone else_ to do it when I'm dead.
   [1]125_missing_infinity_1971-removed-in-1979

References

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