The perpetuity and popularity of Saadi is a clear point that most scholars acknowledge, but the philosophy and mystery behind these features have received little attention. The present study, investigated the factors involved in Saadi and his Golestan’s perpetuity and popularity using a descriptive-analytical method and a critical and comparative point of view. To do so, first, by referring to Saadi's Collections and using critics views the causes and factors behind Sadi's works presented in three linguistic, literary, and intellectual areas. Then, a linguistic feature of Saadi’s Golestan, that is, his accuracy in employing pluralization signs has been critically analyzed as one of the factors for the perpetuity and popularity of this work by extracting examples from the preface and first chapter of this book. The present study shows that using Persian pluralization signs for all Persian words and some Arabic words, choosing Persian words instead of Arabic words which eliminates the use of Arabic rules of pluralization, using irregular and feminine Arabic pluralization signs which are embedded in Persian texts and are not difficult for Persian-speaking audiences, using Persian signs to pluralize Arabic nouns and localizing foreign words, considering the fluency of pronunciation and rhythm of the words in the selection of pluralization signs, and finally, the induction of Saadi's global thought and philanthropy in the form of plural names, are some of the delicacies that appear in the plural words used in Saadi's work. This feature distinguishes Saadi from the writers who use Arabic pluralization signs in order to show their interest in Arabism and consider these characteristics as reasons for the perpetuity and popularity of Saadi's works.