Which artist carried the "organic principle" the farthest, incorporating it even into the structure of his architecture?

The correct answer here is Antoni Gaudi.

Antoni Gaudi is one of the most famous and influential architects in the world and his buildings are one of the main attractions in Spain. He was the practitioner of the Catalan Modernism whose style is characterized by the organic style which is highly inspired and influenced by natural forms. He, to this day, enjoys admiration and global popularity.