 In the Third Meditation, Descartes stresses that insofar as they represent things to us, ideas are real beings, even if the objects they represent do not exist outside thought. The ‘representational reality’ of ideas falls short of the actual being of things in the world but, nevertheless, it is not nothing (AT 7:41, CSM 2:29). He reaffirms this point in the Fifth Meditation and adds that the ideas of various geometrical figures have ‘immutable and eternal’ essences, as is clear from the fact that these ideas resist efforts by our mind to deform them. For example, once I have recognized that having angles equal to two right angles is part of the content of the idea of triangle, I am compelled to recognize this property ‘whether I want to or not’ (AT 7:64, CSM 2:45). In general, Descartes holds that so-called ‘clear and distinct ideas’ are such that I cannot add anything to them or subtract anything from them (AT 7:51, 117–8; CSM 2:35, 83–4). Although he does not mention Descartes as his source, Malebranche develops these points in a way that leads to some very anti-Cartesian conclusions. He too wishes to stress that ideas are real beings and that they resist our mind’s efforts to alter them: