Conrad Gessner was a Renaissance polymath, a physician, philosopher, encyclopaedist, bibliographer, philologist, natural historian and illustrator.

This 473 year old print shows the Bird of Paradise. Gessner developed some marvelous ideas about the life histories of the birds. He suggested that these “Lufftvogels” (birds of the air) were effortlessly suspended by their haloes of plumes. Gessner imagined several uses for these hair-like projections, or cirri —- the naked shafts projecting beyond the rest of the feathers. He speculated that the birds might use them to hang from tree branches when they were tired. They might also be vital to the birds’ love lives: Gessner envisaged couples entwining their cirri together when mating, and as the female sat atop the male to brood her eggs amongst the clouds. He maintained that the fatigue of unending flight might in fact be taken away by the birds’ constant movement, like the perpetual movement of a clock pendulum. He argued, though, that they could not possibly live only on pure air or ether. It was far too thin to sustain anything. They were birds, after all.