Saadi is a poet who gives reasons. His verses in the lyrics are very close to the logical proposition that both contain imaginative elements and the stability of words. One of the ways of creating artistic images and establishing logical ground in lyrics is the style of equation. Saadi in this field was very skillful and by using this technique made his lyrics more artistic and logic. The style of equitation is the subdivision of simile that by combining with allegory led verses to a comprehensible and bright imagination. It talks about common experiences. It joins the mental images of poet with outer images in our world. Saadi by means of allegory smile and its technical subdivision, the style of equation, has composed poetry sometimes in the form of single couplets or quatrains. By proper understanding of brevity, Saadi has used couplets within the framework of style of equation. These couplets are taken from Iranian social fields to demonstrate actual experiences of Iranians with utmost brevity. This causes lyric to be imaginative as well as logical and geometric. Saadi with awareness of his addressees' spirits and psyches, and by means of the style of equation has showed popular philosophy, human tangible experiences, popular sayings, stores, religious and non-religious mythology, and then combined them with mystical and lovely messages.