Humans get enthusiastic when facing certain events and phenomena. One form of such emotions is the act of amazement and surprise which has physiological and cultural roots. It appears that one of the ways to express surprise in Iranian culture is the reaction of "placing a finger to the mouth or teeth" which is considered as a cultural act. In this article, it is sought to discover the history of this reaction, its possible changes in the context of time and why it is used in Iranian painting by applying the descriptive-historical method. To achieve this goal, the situations of astonishment in Persian poetry is investigated in libraries and documents over a period of nearly a thousand years, from the time of Rudaki until contemporary ages. Furthermore, its pictorial samples in Iranian painting in a history of nearly seven hundred years is examined. The results of the research indicate that the reaction to amazement and surprise in the cultural history of Iran is present in Iranian culture for nearly a thousand years without change in form and meaning whilst having a significant presence. It is believed that this reaction is the best method to express amazement with bearing in mind that according to the rules and style of painting, the emotions of the face should not be depicted in Iranian painting. Research aims: 1. A study on the background of the term "finger to tooth / mouth" expression and its possible changes in Iranian poetry and painting. 2. Understanding the reason for using this literary expression in Iranian painting. Research questions: 1. What is the contextual history of the expression "finger to tooth / mouth" and its possible changes in Iranian poetry and painting? 2. What is the reason for applying such an expression in Iranian artworks?