 Another notable consequence of the logical conception of substance is the denial of the causal interaction of finite substances. This is clearest in Primary Truths (C 521/L 269/AG 33), where a very similar argument concerning the nature of substance is given. Not only is it the case, Leibniz claims, that genuine physical influx – the transfer of some property within one substance to a second substance – is inexplicable, but more important the logical conception of substance shows us that the reasons for any property that a substance may have are already contained within its CIC. In other words, every state of a substance is explained, grounded, or caused by its own notion or CIC. (Of course, the ground or reason for the existence or actuality of any particular substance is to be found in God and his free choice of worlds. A more detailed account of Leibniz's views on causation is available in the entry  Leibniz on Causation.)  As we shall see below, the denial of the causal interaction of substances forms an essential premise of Leibniz's argument for pre-established harmony.