this is Jacopo della Quercia
http://www.wga.hu/frames-e.html?/bio/q/quercia/biograph.html
one of the greates students from the Sienese school. he became one of the most known sculpters along side Donatello and Ghiberti. his mayor work was in his natal town of Quercia and was called Fonte Gaia. unfortunately the fountain is greatly damages and only parts of it remain. his sculptures show uncharacteristic, strength and serenity, which won over admirers such as Michelangelo.
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