[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/
2. The text is that of the translation of the Tractatus de Intellectus Emendatione by R. H. M. Elwes, as printed by Dover Publications (NY):1955), ISBN 0-486-20250-X. This text is "an unabridged and unaltered republication of the Bohn Library edition originally published by George Bell and Sons in 1883."
3. Paragraph Numbers, shown thus [1], are from Edwin Curley's translation in his "The Collected Works of Spinoza", Volume 1, 1985, Princeton University Press; ISBN 0-691-07222-1.
4. Sentence Numbers, shown thus (1), have been added by volunteer.