[65] (1) Let us shortly come to our conclusion, and again repeat that we need have no fear of confusing with true ideas that which is only a fiction. (2) As for the first sort of fiction of which we have already spoken, when a thing is clearly conceived, we saw that if the existence of a that thing is in itself an eternal truth fiction can have no part in it; but if the existence of the conceived be not an eternal truth, we have only to be careful such existence be compared to the thing's essence, and to consider the order of nature. (64:3) As for the second sort of fiction, which we stated to be the result of simultaneously directing the attention, without the assent of the intellect, to different confused ideas representing different things and actions existing in nature, we have seen that an absolutely simple thing cannot be feigned, but must be understood, and that a complex thing is in the same case if we regard separately the simple parts whereof it is composed; we shall not even be able to hypothesize any untrue action concerning such objects, for we shall be obliged to consider at the same time the causes and manner of such action. [66] (1) These matters being thus understood, let us pass on to consider the false idea, observing the objects with which it is concerned, and the means of guarding ourselves from falling into false perceptions. (2) Neither of these tasks will present much difficulty, after our inquiry concerning fictitious ideas. (3) The false idea only differs from the fictitious idea in the fact of implying a mental assent--that is, as we have already remarked, while the representations are occurring, there are no causes present to us, wherefrom, as in fiction, we can conclude that such representations do not arise from external objects: in fact, it is much the same as dreaming with our eyes open, or while awake. (67:4) Thus, a false idea is concerned with, or (to speak more correctly) is attributable to, the existence of a thing whereof the essence is known, or the essence itself, in the same way as a fictitious idea. [67] (1) If attributable to the existence of the thing, it is corrected in the same way as a fictitious idea under similar circumstances. (2) If attributable to the essence, it is likewise corrected in the same way as a fictitious idea. (67:3) For if the nature of the thing known implies necessary existence, we cannot possible be in error with regard to its existence; but if the nature of the thing be not an eternal truth, like its essence, but contrariwise the necessity or impossibility of its existence depends on external causes, then we must follow the same course as we adopted in the of fiction, for it is corrected in the same manner.