The Interpretation of Dreams by Sigmund Freud Chapter 4 Page 11

I think she has actually done this, and as a sign of this identification she has created an unfulfilled wish in reality. But what is the meaning of this hysterical identification? To clear this up a thorough exposition is necessary. Identification is a highly important factor in the mechanism of hysterical symptoms; by this means patients are enabled in their symptoms to represent not merely their own experiences, but the experiences of a great number of other persons, and can suffer, as it were, for a whole mass of people, and fill all the parts of a drama by means of their own personalities alone.

It will here be objected that this is well-known hysterical imitation, the ability of hysteric subjects to copy all the symptoms which impress them when they occur in others, as though their pity were stimulated to the point