Full Idea
It is for lack of reflection on themselves that beasts have no moral qualities.
Gist of Idea
Animals lack morality because they lack self-reflection
Source
Gottfried Leibniz (Discourse on Metaphysics [1686], §34)
Book Reference
Leibniz,Gottfried: 'Philosophical Writings', ed/tr. Parkinson,G.H.R. [Dent 1973], p.43
A Reaction
Interesting, but I think this is false. I would say animals do have a sense of their self, because that is the most basic feature of any mind, but what they lack is second-order thought, that is, ability to reflect on and judge their own beliefs and acts.