Full Idea
It is only to things which are indistinguishable and one in essence [ousia] that all the same attributes are generally held to belong.
Gist of Idea
Only if two things are identical do they have the same attributes
Source
Aristotle (Sophistical Refutations [c.331 BCE], 179a37)
Book Reference
Aristotle: 'Sophistical Refutations, On the Cosmos etc (III)', ed/tr. Forster,E.S. /Furley,D.J. [Harvard Loeb 1955], p.121
A Reaction
This simply IS Leibniz's Law (to which I shall from now on quietly refer to as 'Aristotle's Law'). It seems that it just as plausible to translate 'ousia' as 'being' rather than 'essence'. 'Indistinguishable' and 'one in ousia' are not the same.