Chance \Chance\ (ch[.a]ns), n. [F. chance, OF. cheance, fr. LL.
   cadentia a allusion to the falling of the dice), fr. L.
   cadere to fall; akin to Skr. [,c]ad to fall, L. cedere to
   yield, E. cede. Cf. Cadence.]
   1. A supposed material or psychical agent or mode of activity
      other than a force, law, or purpose; fortune; fate; -- in
      this sense often personified.
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            It is strictly and philosophically true in nature
            and reason that there is no such thing as chance or
            accident; it being evident that these words do not
            signify anything really existing, anything that is
            truly an agent or the cause of any event; but they
            signify merely men's ignorance of the real and
            immediate cause.                      --Samuel
                                                  Clark.
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   Note: Many of the everyday events which people observe and
         attribute to chance fall into the category described by
         Clark, as being in practice too complex for people to
         easily predict, but in theory predictable if one were
         to know the actions of the causal agents in great
         detail. At the subatomic level, however, there is much
         evidence to support the notion derived from
         Heisenberg's uncertaintly principle, that phenomena
         occur in nature which are truly randomly determined,
         not merely too complex to predict or observe
         accurately. Such phenomena, however, are observed only
         with one or a very small number of subatomic particles.
         When the probabilities of observed events are
         determined by the behavior of aggregates of millions of
         particles, the variations due to such quantum
         indeterminacy becomes so small as to be unobservable
         even over billions of repetitions, and may therefore be
         ignored in practical situations; such variations are so
         improbable that it would be irrational to condition
         anything of consequence upon the occurrence of such an
         improbable event. A clever experimenter, nevertheless,
         may contrive a system where a very visible event (such
         as the dynamiting of a building) depends on the
         occurrence of a truly chance subatomic event (such as
         the disintegration of a single radioactive nucleus). In
         such a contrived situation, one may accurately speak of
         an event determined by chance, in the sense of a random
         occurrence completely unpredictable, at least as to
         time.
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               Any society into which chance might throw him.
                                                  --Macaulay.
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               That power
               Which erring men call Chance.      --Milton.
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   2. The operation or activity of such agent.
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            By chance a priest came down that way. --Luke x. 31.
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   3. The supposed effect of such an agent; something that
      befalls, as the result of unknown or unconsidered forces;
      the issue of uncertain conditions; an event not calculated
      upon; an unexpected occurrence; a happening; accident;
      fortuity; casualty.
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            In the field of observation, chance favors only the
            mind that is prepared.                --Louis
                                                  Pasteur.
      [PJC]

   Note: This quotation is usually found in the form "Chance
         favors the prepared mind." It is a common rejoinder to
         the assertion that a scientist was "lucky" to have made
         some particular discovery because of unanticipated
         factors. A related quotation, from the
         Nobel-Prize-winning chemist R. B. Woodward, is that "A
         scientist has to work wery hard to get to the point
         where he can be lucky."
         [PJC]

               It was a chance that happened to us. --1 Sam. vi.
                                                  9.
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               The Knave of Diamonds tries his wily arts,
               And wins (O shameful chance!) the Queen of
               Hearts.                            --Pope.
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               I spake of most disastrous chance. --Shak.
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   4. A possibility; a likelihood; an opportunity; -- with
      reference to a doubtful result; as, a chance to escape; a
      chance for life; the chances are all against him.
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            So weary with disasters, tugged with fortune.
            That I would get my life on any chance,
            To mend it, or be rid on 't           --Shak.
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   5. (Math.) Probability.
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   Note: The mathematical expression, of a chance is the ratio
         of frequency with which an event happens in the long
         run. If an event may happen in a ways and may fail in b
         ways, and each of these a + b ways is equally likely,
         the chance, or probability, that the event will happen
         is measured by the fraction a/a + b, and the chance, or
         probability, that it will fail is measured by b/a + b.
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   Chance comer, one who comes unexpectedly.

   The last chance, the sole remaining ground of hope.

   The main chance, the chief opportunity; that upon which
      reliance is had, esp. self-interest.

   Theory of chances, Doctrine of chances (Math.), that
      branch of mathematics which treats of the probability of
      the occurrence of particular events, as the fall of dice
      in given positions.

   To mind one's chances, to take advantage of every
      circumstance; to seize every opportunity.
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