As far as I can see, the partition of a dream into two unequal portions does not always signify a causal relation between the thoughts of the two portions. It often appears as though the same material were being presented in the two dreams from different points of view; or as though the two dreams have proceeded from two separated centres in the dream material and their contents overlap, so that the object which is the centre of one dream has served in the other as an allusion, and _vice versa_. But in a certain number of cases a division into shorter fore-dreams and longer subsequent dreams actually signifies a causal relation between the two portions. The other method of representing causal relation is used with less abundant material and consists in the change of one image in the dream, whether a person or a thing, into another. It is only in cases where we witness this change taking place in the dream that any causal relation is asserted to exist, not where we merely notice that one thing has taken the place of another. I said that both methods of representing causal relation are reducible to the same thing; in both cases _causation_ is represented by a _succession_, now by the sequence of the dreams, now by the immediate transformation of one image into another. In the great majority of cases, of course, causal relation is not expressed at all, but is obliterated by the sequence of elements which is unavoidable in the dream process. The dream is altogether unable to express the alternative, “either—or”; it is in the habit of taking both members of this alternative into one context, as though they were equally privileged. A classic example of this is contained in the dream of Irma’s injection. Its latent thoughts obviously mean: I am innocent of the continued presence of Irma’s pains; the fault rests either with her resistance to accepting the solution, _or_ with the fact that she is living under unfavourable sexual conditions, which I am unable to change, _or_ her pains are not of a hysteric nature at all, but organic. The dream, however, fulfils all these possibilities, which are almost exclusive, and is quite ready to extract from the dream-wish an additional fourth solution of this kind. After interpreting the dream I have therefore inserted the _either—or_ in the sequence of the dream thoughts.