Composed of coloured pencil, ink and graphite on graph paper, Dan Flavin’s brightly coloured blue and yellow geometric drawing from 1970, Untitled (to Marianne) 2, gives a fascinating insight into the makings of the artist’s hallmark light sculptures for which he is world renowned. The work is one of a number of sketches Flavin created outlining his concepts for his large and ambitious gallery installations, which were exhibited as part of a group exhibition at the Leo Castelli Gallery in 1970. Untitled (to Marianne) 2 depicts the design for a blue and yellow fluorescent light structure, characteristically positioned in the corner space between two walls. This enchanting work, more than simply a blueprint, is markedly artistic in character: flanking the boldly coloured blocks on either side are two white bars which have been delicately outlined in opposing colour – blue besides the yellow block and yellow besides the blue – giving the alluring appearance of an incandescent glow. Although the installation was never realised, the ‘2’ in the title distinguishes it from a simplified variation of the design with the same title and colour scheme, which was fabricated three times. With elegantly cursive penmanship, Flavin has inscribed the present work with a dedication to Marianne Barcelona who worked at the Leo Castelli Gallery at the time of the group exhibition. Detailing the creative process behind Flavin’s sculptural creations, this vibrant drawing both highlights the artist’s pioneering practice of reshaping and redefining space through the medium of light, and presents a beautiful artistic vision in its own right.