Arnold Klein (plaintiff) applied for a patent disclosing a device used for preparing nectar for bird and butterfly feeders. The specification described a container with an adjustable divider creating two compartments of differing volumes for sugar and water depending upon the type of nectar being made. Once the container was filled and the divider removed, the sugar and water mixed to create the nectar. The patent examiner rejected Klein’s application, finding it invalid for obviousness under 35 U.S.C § 103(a) in light of prior art patents held by Roberts, O’Connor, Kirkman, Greenspan, and De Santo. The Roberts, O’Connor, and Kirkman patents taught drawer organization designs, with movable dividers that separated drawers into compartments of varying sizes to organize different-sized items. The Greenspan patent disclosed a bottle comprised of two compartments, one for plasma and one for water, separated by a plugged, nonadjustable wall. Removing the plug allowed the plasma and water to mix. Similarly, the De Santo patent disclosed a fluid container with two compartments separated by a fixed wall, which could be removed to allow the ingredients to mix. Klein appealed, contending that the references were not analogous art for purposes of an obviousness inquiry. The Board of Patent Appeals and Interferences (Board) affirmed, finding the references each disclosed a container with a divider that could be used to separate ingredients into varying ratios. The Board concluded that a person having ordinary skill in the art would have had reason to combine the prior art references with already known sugar to water ratios to create different nectars. Klein appealed.