There is no doubt that we can observe a full of sense and exiting dance of line in the works of those artists who have been educated in a land in which there is the culture and people whose taste in expressing their feelings and their pure and theosophical inside thoughts lead to poem. If a nation is loyal to a word or ambition within centuries, we can follow close ties and common interests when these come into drawing and appearance, these are the result of a common spirit. There is interest in the kind of line and way of drawing it within history which has become the symbol and trait of a nation in order to become the identity and basis of Iranian patterns. There is a special kind of "grow" and "movement" in Iranian patterns and models which are inspired to the viewer through a special kind of line. This makes the patterns independent to time for the addressee. A curve is related to man nature and because of its smoothness makes people feel calm and comfort. The joint shape in most of the Iranian arts over the centuries is the main point in this investigation. Smoothness and curve is revealed in most aspect of Iranian arts for example bas-relief of Takhte Jamshid and figures gesture in the book of Shahname Shahtamasbi. Among all kind of curve, one of them is more popular and common in Iranian arts for example wrinkle of clothes in the paintings and on mosques tiles. The basic shape of it somehow looks like a tear, which is also revealed in Iranian calligraphy. What makes Iranian calligraphy distinct from other ones is its tendency of curve and movement in spite of assertion. Choosing and investigating this basic line which has been formed in the bed of curve and arch can present the special national taste of the people of a land and it has emotional and mental response within people spirit. The line basic movement of has been rooted in the Iranian mind in all of the centuries. With regards to this matter, this research studies history of curve in the nature of people and its use in Iranian art. Here by Iranian art we don't mean a specific art and technique but we mean to achieve a generalization and a clear curve which exists in the spirit of Iranian patterns and forms. The line element is one of the most important visual and eternal aspect of the Iranian art. This element as an joint sprite associated Iranian arts in spite of many evolutions over centuries. This research aims to answer below questions: 1-Is there fix line and pattern which are in conformity with individual and national taste of Iranians? 2-What elements have line and form been made from and what concept do they have? 3-What is the place (status) of line in Iranian patterns and when and how it is used?
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