Full Idea
Omnipotent will cannot make things like or equal one to another, without the natures of likeness and equality.
Gist of Idea
An omnipotent will cannot make two things equal or alike if they aren't
Source
Ralph Cudworth (On Eternal and Immutable Morality [1688], Ch.II.I)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.107
A Reaction
This is one of the many classic 'paradoxes of omnipotence'. The best strategy is to define omnipotence as 'being able to do everything which it is possible to do'. Anything beyond that is inviting paradoxical disaster.