The Collaborative International Dictionary of English v.0.48:

Delve \Delve\v. t. [imp. & p. p. Delved; p. pr. & vb. n.
   Delving.] [AS. delfan to dig; akin to OS. bidelban to bury,
   D. delven to dig, MHG. telben, and possibly to E. dale. Cf.
   Delf a mine.]
   1. To dig; to open (the ground) as with a spade.
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            Delve of convenient depth your thrashing floor.
                                                  --Dryden.
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   2. To dig into; to penetrate; to trace out; to fathom.
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            I can not delve him to the root.      --Shak.
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