E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Let,
to permit, is the Anglo-Saxon lœt-an, to suffer or permit; but let (to hinder) is the verb lett-an. It is a pity we have dropped the second t in the latter word.
1
“Oftentimes I purposed to come unto you, but was [have been] let hitherto.”—Romans i. 18.
