the X that can be Y is not the true X

from Jargon File (4.4.4, 14 Aug 2003)
the X that can be Y is not the true X


   Yet another instance of hackerdom's peculiar attraction to mystical
   references -- a common humorous way of making exclusive statements
   about a class of things. The template is from the Tao te Ching: "The
   Tao which can be spoken of is not the true Tao." The implication is
   often that the X is a mystery accessible only to the enlightened. See
   the {trampoline} entry for an example, and compare {has the X nature}.
    
from The Free On-line Dictionary of Computing (8 July 2008)
the X that can be Y is not the true X

   Yet another instance of hackerdom's peculiar attraction to
   mystical references - a common humorous way of making
   exclusive statements about a class of things.  The template is
   from the "Tao te Ching": "The Tao which can be spoken of is
   not the true Tao."  The implication is often that the X is a
   mystery accessible only to the enlightened.  See the
   {trampoline} entry for an example, and compare {has the X
   nature}.

   [{Jargon File}]
    

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