 In his response, Malebranche attempts to exploit Régis’ suggestion but without leaving the door open to Cartesianism. Lacking causal efficacy and being ‘invisible’ in themselves, bodies cannot act directly on the mind in the way that Régis had indicated. In virtue of being in God, however, the idea of extension can ‘affect’ or ‘touch’ the mind in various ways (OC 17–1, 282–3). In changes made to previously published works, two years later (1695), Malebranche even more explicitly ties the intelligibility of ideas to their causal efficacy (Robinet 1965, 259, note 2). Readers are told for the first time that the reason ideas are intelligible and bodies are not is because only the former can act on the mind.