[61a] (1) Though I seem to deduce this from experience, some may deny its cogency because I have given no formal proof. (2) I therefore append the following for those who may desire it. (3) As there can be nothing in nature contrary to nature's laws, since all things come to pass by fixed laws, so that each thing must irrefragably produce its own proper effect, it follows that the soul, as soon as it possesses the true conception of a thing, proceeds to reproduce in thought that thing's effects. (4) See below, where I speak of the false idea. [64b] (1) Observe that fiction regarded in itself, only differs from dreams in that in the latter we do not perceive the external causes which we perceive through the senses while awake. (2) It has hence been inferred that representations occurring in sleep have no connection with objects external to us. (3) We shall presently see that error is the dreaming of a waking man: if it reaches a certain pitch it becomes delirium. [76z] These are not attributes of God displaying His essence, as I will show in my philosophy. [76a] (1) This has been shown already. (2) For if such a being did not exist it would never be produced; therefore the mind would be able to understand more than nature could furnish; and this has been shown above to be false. [78a] (1) That is, it is known that the senses sometimes deceive us. (2) But it is only known confusedly, for it is not known how they deceive us. [83d] (1) If the duration be indefinite, the recollection is imperfect; this everyone seems to have learnt from nature. (2) For we often ask, to strengthen our belief in something we hear of, when and where it happened; though ideas themselves have their own duration in the mind, yet, as we are wont to determine duration by the aid of some measure of motion which, again, takes place by aid of imagination, we preserve no memory connected with pure intellect. [91e] The chief rule of this part is, as appears from the first part, to review all the ideas coming to us through pure intellect, so as to distinguish them from such as we imagine: the distinction will be shown through the properties of each, namely, of the imagination and of the understanding. [92f] Observe that it is thereby manifest that we cannot understand anything of nature without at the same time increasing our knowledge of the first cause, or God. End of "On the Improvement of the Understanding." Notes by Volunteer. 1. Used, in part, with kind permission from: http://www.physics.wisc.edu/~shalizi/Spinoza/TIE/