[f. SOUND v.2] Of water, the sea, etc.: That cannot be sounded; unfathomable. Freq. fig. or in fig. context.

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c. 1586.  C’tess Pembroke, Ps. CXLVIII. iv. When heav’n hath prais’d, praise earth anew:… Then soundlesse deepes, and what in you Residing low, or moves, or rests.

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c. 1600.  Shaks., Sonn., lxxx. 10. Your shallowest helpe will hold me vp a floate, Whilst he vpon your soundlesse deepe doth ride.

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1647.  Herrick, Noble Numbers, Hell. Hell is no other, but a soundlesse pit.

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1731.  A. Hill, Advice to Poets, xv. In Wit’s cold Shallows, wade … no more, Her soundless Ocean tempts you from the Shore.

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1823.  Byron, Island, IV. iii. The crag’s steep inexorable face, With nought but soundless waters for its base.

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a. 1861.  T. Woolner, My Beautiful Lady, Tolling Bell, xxvi. My lost soul sank adown in soundless seas.

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1885.  [W. H. White], M. Rutherford’s Deliv., iv. 75. When we consider that we live surrounded by the soundless depths in which the stars repose.

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  transf.  1614.  C. Brooke, Ghost Rich. III., Poems (1872), 79.

        Nor wits, nor chronicles could ere containe,
The hell-deepe reaches of my soundlesse braine.

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