To avail ones self of

from The Collaborative International Dictionary of English v.0.48
Avail \A*vail"\, v. t. [imp. & p. p. {Availed} (?); p. pr. & vb.
   n. {Availing}.] [OE. availen, fr. F. ? (L. ad) + valoir to be
   worth, fr. L. valere to be strong, to be worth. See
   {Valiant}.]
   1. To turn to the advantage of; to be of service to; to
      profit; to benefit; to help; as, artifices will not avail
      the sinner in the day of judgment.
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            O, what avails me now that honor high ! --Milton.
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   2. To promote; to assist. [Obs.] --Pope.
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   {To avail one's self of}, to make use of; take advantage of.
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            Then shall they seek to avail themselves of names.
                                                  --Milton.
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            I have availed myself of the very first opportunity.
                                                  --Dickens.
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