Related:

• One man's constant is another man's variable. -- A.J. Perli
• One person's constant is another person's variable.
  -- Alan J. Perlis, "Programming Pearls", Communications of the ACM, Sep. 1985...
• The materials of action are variable, but the use we make of them should be constant.
  -- Epictetus (c. 60 AD) -- How Nobleness of Mind may be consistent with Prudence, -- Discourses, Book ii, Chap....
• The primary purpose of the DATA statement is to give names to consta
  instead of referring to pi as 3.141592653589793 at every appearance, the variable PI can be given that value with a DATA statement and used instead of the longer form of the constant....
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