fundamental arguments against innate ideas is the very fact that there is no truth to which all people attest. He took the time to argue against a number of propositions that rationalists offer as universally accepted truth, for instance the principle of identity, pointing out that at the very least children and idiots are often unaware of these propositions. In anticipating a counterargument, namely the use of reason to comprehend already existent innate ideas, Locke states that "by this means, there will be no difference between the maxims of the mathematicians, and theorems they deduce from them; all must be equally allowed innate; they being all discoveries made by the use of reason." Book II Whereas Book I is intended to reject the doctrine of innate ideas proposed by Descartes and the rationalists, Book II explains that every idea is derived from experience either by sensation—i.e. direct sensory information—or reflection—i.e. "the perception of the operations of our own mind within us, as it is employed about the ideas it has got." In Book II, Locke focuses on the ideas of substances and qualities, in which the former are "an unknown support of qualities" and latter have the "power to produce ideas in our mind." Substance is what holds qualities together, while qualities themselves allow us to perceive and identify objects. A substance consists of bare particulars and does not have properties in themselves except the ability to support qualities. Substances are "nothing but the assumption of an unknown support for a group of qualities that produce simple ideas in us." Despite his explanation, the existence of substances is still questionable as they cannot necessarily be "perceived" by themselves and can only be sensed through the qualities. In terms of qualities, Locke divides such into primary and secondary, whereby the former give our minds ideas based on sensation and actual experience. In contrast, secondary qualities allow our minds to understand something based on reflection, in which we associate what we perceive with other ideas of our own. Furthermore, Book II is also a systematic argument for the existence of an intelligent being:Thus, from the consideration of ourselves, and what we infallibly find in our own constitutions, our reason leads us to the knowledge of this certain and evident truth, that there is an eternal, most powerful, and most knowing being; which whether any one will please to call God, it matters