Introduction
According to the Conceptual Metaphor Theory, metaphor is the result of cognitive patterns in the mind and it is part of the thought. In this view metaphor is a mechanism for conceptualization and each concept to any extend abstract and complex, can be structured by various metaphors which each of them is a part of comprehensive metaphorical systems, together achieve the complex goal of describing that concept with its all aspects as we understand them. Although such metaphors do not present a single continuous objective image; they are overlapping and hence have coherence.
World concept is an abstract concept that has been usually taken into account in Persian literature. In present research the main issue is to study the overlapping of “world” structural metaphors in Sa’adi’s and Parvin’s poems. This study has been concentrated on “world” structural metaphors to answer the following questions: a) what are the structural metaphors of “world” target domain in Sa’adi’s and Parvin’s poems? b) How is metaphorical coherence and overlap of “world” structural metaphors in both poets’ poems?
A study that has paid its attention on overlapping and coherence of metaphors is for Hezaji and other (2020) by the name of “The Process of Coherence between the Conceptual Metaphors of the Holy Quran”. The researchers found Quran’s metaphorical language has offered coherence to all the desired concepts and thoughts towards its main goal. Among studies have been done about Life concept that is similar to World concept is Charteris-Black’s study (2017) that has surveyed metaphors of competition and ideology. He concluded that the effort for the creation of power is the result of ideological metaphor “Life as a race”. Luo (2018) by a corpus-based study on Life concept has discovered Chinese Life metaphors on the base of the cognitive linguistics approach.
This research is a theoretical descriptive-analytic research. To find answers to questions, after mentioning the background; first Lakoff and Jhonsn’s (2003) cognitive perspective about metaphors and metaphorical coherence has been studied. Then based on the concepts of this view, the overlapping of metaphors of “world” in poems of Sa’adi and Parvin has been examined. Data have been gathered from Sa’adi’s (2002) and Parvin’s (2018) Ghasides and Ghetaas by taking notes. For discovering “world” structural metaphor, it was an attempt for extraction of both categories of explicit and contextual metaphorical mappings from the text through a deep studying. Then quantitative and qualitative comparison and analysis was done. It is noteworthy that some poems have had more than a “world” conceptual metaphor; therefore they have been repeated in related conceptual metaphors. In present research for each poet 1200 Ghasides and Ghetaas were chosen by random sampling method.
 
Review
The survey of the structural metaphors of “world” in Sa’adi’s and Parvin’s poems shows because of the abstract essence of the concept and hence lack of its clarity, both poets have tried to express it through metaphors. Metaphors “world is journey”; “world is building”; “world is farm” in both poets’ poems convey a solid cultural foundation and are overlapped and hence have coherence. The base of overlapping of the mentioned metaphors is highlighting surface, progress, and content in a different way. In “world is journey” the surface can be passed by a specified program, in addition; its content is our behaviors on this path. In “world is building” the surface is the foundation and its content is life. In “world is farm” the surface is covered by careful attention to actions and behavior and its content determines the type of the life after death. Although each of the World metaphors in both poets’ poems makes understandable one aspect of life; altogether concentrate on all aspects of “world”. These metaphors in both poets’ poems grounded in correlation within their experience and conception of world; however, metaphorical variety of “world” concept is more in Parvin’s poems, generally there is an overlap among their aims.
 
Conclusion
The findings show among 94 extracted “world” structural metaphors, 21 have been seen in Sa’adi’s poems and 73 have been discovered in Parvin’s poems. Common structural source domains in both poets’ poems for conceptualizing “world” are building, journey, sea, farm, economy and war. Furthermore, the frequency of occurrence of structural metaphors “world is journey”; “world is building”; “world is farm” is high in both poets’ poems. The metaphor “world is farm” refers to the importance and role of how to live and shows the content of life for achieving the goals. The mentioned metaphor is overlapped with metaphors “world is journey” and “world is building”.