Gaudí was searching for a new column, one that would excel the earlier ones but would fit into the history of the column. And, in that history, he saw three great basic models:
1) The Greek Doric column has vertical grooves.
2) The Corinthian order column, which is cylindrical, is generated by the extrusion of the circle from the base following a slightly curved profile.
3) The barley sugar column, typical of the Baroque, with the torus shape, marks an ascending helicoidal movement following the helix that surrounds the cylinder of the nucleus.
Gaudí considered the double twisted column the synthesis of the architectural column since it combines parts of the three historical models. It springs from a star-shaped base but reaches the circle; it has a number of grooves engraved on it, and more appear as it rises; and it has the helicoidal movement of the barley sugar columns but twice. (http://www.sagradafamilia.cat)
Graphic published in El Mundo, Svenska, Sole, Nación y El Observador, by Julian De Velasco and Jesús Gil. (http://www.flickr.com/photos/30944919@N03/5159504104/)