Not to be sneezed at

Mostly appears in this negative form and means not to be taken lightly or not to be treated with scorn. It first appears in a play by the English dramatist George Colman the Younger (1762-1836) The Heir-at-Law performed at the Haymarket theatre in London in 1797. Act II, Scene I, “two hundred pounds, nowadays, are not to be sneezed at”. Because it was featured in a play at that time indicates the expression was well known. The OED maintains that to sneeze at, means to regard something as little value, worth or consideration but says that it is chiefly used in the negative form and cites 1806 as the first attestation of this. One imagines that the expression has always been used figuratively and in the negative form because of the difficulty of summoning up a sneeze every time one wished to convey that something was of little value.