Full Idea
In nature any straight line you may take is individually different from any other straight line you may find. Accordingly, it cannot come about that two bodies are perfectly equal and alike.
Gist of Idea
In nature there aren't even two identical straight lines, so no two bodies are alike
Source
Gottfried Leibniz (Letters to Burcher De Volder [1706], 1703.06.20)
Book Reference
Leibniz,Gottfried: 'Leibniz Selections', ed/tr. Wiener,Philip P. [Scribners 1951], p.180
A Reaction
Leibniz was very good at persuasive examples! It remains unclear, though, why he takes the Identity of Indiscernibles to be a necessary truth, when he seems to have only observed it from experience. This is counter to his other principles.