The fact that in the personality of the loved object there often lies hidden, as it were, the buried image of a brother, sister, parent or other object of incestuous affection in the past, would seem to play an important part in the formation of a type of story of world-wide occurrence, of which the Cupid-Psyche myth and the Lohengrin legend are perhaps the best known examples[117]. In these stories a marriage or love affair takes place between partners, one of whom is usually of mysterious (sometimes divine) origin and consents to enter upon the alliance only upon the condition that no question shall be asked as to his (or her) name, parentage or home; or upon the erection of some other prohibition, such as one which forbids the use of vision or of speech (either generally or under specified circumstances); upon the infringement of which conditions the mysterious partner vanishes, leaving the remaining member of the pair to lament the loss that has been thus foolishly incurred through curiosity. Here the prohibition would seem to be imposed with a view to concealing the fact that the union is based ultimately upon the foundation of an incestuous affection, or is itself incestuous in nature: a recognition of this fact would spoil the pleasure of the union by arousing the repressions connected with incestuous love and must therefore (as in the case of the marriage between Œdipus and Jocasta in the Œdipus myth, where Jocasta--in Sophocles' play--strenuously opposes all efforts at investigation) be prevented by the most rigorous prohibitions, the breaking of which involves the permanent dissolution of the union. [Sidenote: Similarity as a basis of displacement] [Sidenote: Its biological significance]