When artists use collage, they incorporate elements that come from the world into their drawings, paintings and sculptures. Put within a new context, these elements take on new meanings. The image above is a detail of one of El Anatsui's amazing pieces. His inspiring work was on display in his one person exhibition at the Brooklyn Museum in 2013. Here is a link to more information about the exhibition: Gravity and Grace: Monumental Works by El Anatsui.