错误的呈现往往指出这个人的心智受到某种力量的干扰，正陷于激烈的心理斗争中。但是潜抑的侵扰思绪的性质，并不决定错误的特定方式，许多单纯的语误和笔误也有类似的情形。每次我们犯了语误或笔误，在不知不觉中我们的心理历程都正遭受着侵扰。问题是，它们常常不透露侵扰成分的性质，而只是按着“相似”与“方便”的规则，表现出一种明显的倾向。
Of all parapraxes errors seem to have the least rigid mechanism. That is to say, the occurrence of an error is a quite general indication that the mental activity in question has had to struggle with a disturbing influence of some sort or other; but the particular form that the error takes is not determined by the quality of the concealed disturbing idea. We may add here retrospectively that the same thing can be assumed to be true of many simple cases of slips of the tongue and pen. Every time we make a slip in talking or writing we may infer that there has been a disturbance due to mental processes lying outside our intention; but it must be admitted that slips of the tongue and of the pen often obey the laws of resemblance, of indolence or of the tendency to haste, without the disturbing element succeeding in imposing any part of its own character on the resulting mistake in speech or writing. It is the compliance of the linguistic material which alone makes the determining of the mistakes possible, and at the same time sets the limits up to which the determining can go.引自 第十章：错误
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