Full Idea
'There is nothing that an omnipotent power could not do?' 'No.' 'Then can God do evil?' 'No.' 'So evil is nothing, since that is what He cannot do who can do anthing.'
Gist of Idea
God can do anything, but he cannot do evil, so evil must be nothing
Source
Boethius (The Consolations of Philosophy [c.520], III.XII)
Book Reference
Boethius: 'The Consolations of Philosophy', ed/tr. Watts,V.E. [Penguin 1969], p.112
A Reaction
A lovely example of the contortions necessary once you insist that God must be 'omnipotent', in some absolute sense of the term. Saying that evil is 'nothing' strikes me as nothing more than a feeble attempt to insult it.