This article deals with the study of the plot invariant and its variability that occurs on the level of the linguistic structure of texts. The material of research is based on Middle English folklore texts. The author tries to show the notion of variation as a process taking into account literature and linguistic stability and variability of the folk texts. Becoming more resultative even in the theory of translation, the concept of invariant for an interpreter is the idea that should remain unchanged and understood as information to be passed on, while an expressed idea is becoming a variant already.
The form whose main function is to express indirect commands, called the third person Imperative, Jussive or Exhortative, when compared to the prototypical (second person) Imperative, shows semantic and formal similarities and distinctions at the same time. The study describes formal and functional patterns of Jussive and places this category within the typology of the related categories, such as Imperative and Optative, based on data from six East Caucasian languages (Archi, Agul, Akhvakh, Chechen, Icari and Kumyk). Five formal patterns of Jussive are attested in these languages, including a specialized form, constructions derived from want, from tell him to do and from make him do and the Optative. Jussive forms may express such meanings as third person command, indirect causation, permission, indifference towards the accomplishment of an action and an assumption. While the Jussive is crucially different from the second person Imperative in that it introduces a third participant, this article shows that it is the addressee, not a third person, who is the central participant of a Jussive situation from both formal and functional points of view.