Now, is this the explanation of all tongue slips? I am very much inclined to think so and for this reason, that as often as one investigates a case of a slip of the tongue, it reduces itself to this type of explanation. But on the other hand, one cannot prove that a slip of the tongue cannot occur without this mechanism. It may be so; for our purposes it is a matter of theoretical indifference, since the conclusions which we wish to draw by way of an introduction to psychoanalysis remain untouched, even if only a minority of the cases of tongue slips come within our conception, which is surely not the case. I shall anticipate the next question, of whether or not we may extend to other types of errors what we have gleaned from slips of the tongue, and answer it in the affirmative. You will convince yourselves of that conclusion when we turn our attention to the investigation of examples of pen slips, picking up wrong objects, etc. I would advise you, however, for technical reasons, to postpone this task until we shall have investigated the tongue slip itself more thoroughly. The question of what meaning those factors which have been placed in the foreground by some authors,--namely, the factors of circulatory disturbances, fatigue, excitement, absent-mindedness, the theory of the distraction of attention--the question of what meaning those factors can now have for us if we accept the above described psychic mechanism of tongue slips, deserves a more detailed answer. You will note that we do not deny these factors. In fact, it is not very often that psychoanalysis denies anything which is asserted on the other side. As a rule psychoanalysis merely adds something to such assertions and occasionally it does happen that what had hitherto been overlooked, and was newly added by psychoanalysis, is just the essential thing. The influence on the occurrence of tongue slips of such physiological predispositions as result from slight illness, circulatory disturbances and conditions of fatigue, should be acknowledged without more ado. Daily personal experience can convince you of that. But how little is explained by such an admission! Above all, they are not necessary conditions of the errors. Slips of the tongue are just as possible when one is in perfect health and normal condition. Bodily factors, therefore, have only the value of acting by way of facilitation and encouragement to the peculiar psychic mechanism of a slip of the tongue.