We will now start a research, not with axioms. For this purpose, we will select some phenomena that are very common, well-known, and often overlooked, and which have no relation to illness, since we can observe them in every healthy individual.

I mean the mistakes one makes when trying to express something and uses the wrong word (slip of the tongue) or when the same mistake occurs in writing (slip of the pen) which in this case may be noticed or not, or when someone reads in print or handwritten something different from what is actually in front of them (reading error) or when someone mishears what they are told, of course, when there is no illness of the auditory sensory organ.

Another series of such phenomena is those where someone temporarily forgets something but not definitively. That is, when someone cannot remember a name they know well and that they are always capable of remembering every time they hear it.

[Excerpt from the text on the back cover of the edition]