Now, in my work on the _Interpretation of Dreams_ I have shown the part played by the process of condensation in the origin of the so-called manifest contents of the dream from the latent thoughts of the dream. Any similarity of objects or of word-presentations between two elements of the unconscious material is taken as a cause for the formation of a third, which is a composite or compromise formation. This element represents both components in the dream content, and in view of this origin it is frequently endowed with numerous contradictory individual determinants. The formation of substitutions and contaminations in speech-mistakes is, therefore, the beginning of that work of condensation which we find taking a most active part in the construction of the dream. In a small essay destined for the general reader,[15] Meringer advanced a theory of very practical significance for certain cases of interchanging of words, especially for such cases where one word is substituted by another of opposite meaning. He says: “We may still recall the manner in which the President of the Austrian House of Deputies opened the session some time ago: ‘Honoured Sirs! I announce the presence of so and so many gentlemen, and therefore declare the session as “closed”’!” The general merriment first attracted his attention and he corrected his mistake. In the present case the probable explanation is that the President wished himself in a position to close this session, from which he had little good to expect, and the thought broke through at least partially--a frequent manifestation--resulting in his use of “closed” in place of “opened,” that is, the opposite of the statement intended. Numerous observations have taught me, however, that we frequently interchange contrasting words; they are already associated in our speech consciousness; they lie very close together and are easily incorrectly evoked. Still, not in all cases of contrast substitution is it so simple as in the example of the President as to appear plausible that the speech-mistake occurs merely as a contradiction which arises in the inner thought of the speaker opposing the sentence uttered. We have found the analogous mechanism in the analysis of the example _aliquis_; there the inner contradiction asserts itself in the form of forgetting a word instead of a substitution through its opposite. But in order to adjust the difference we may remark that the little word _aliquis_ is incapable of a contrast similar to “closing” and “opening,” and that the word “opening” cannot be subject to forgetting on account of its being a common component of speech.