Who can fondly remember scanning a dozen images, mucking about in Photoshop – drawing with a a rollerball mouse and then attempting to save the ART all to a single floppy disc?

Adobe Photoshop 2.5, running on a Apple Macintosh IIsi in early 1994

Humoral theory, also known as humorism or the theory of the four humours, was a model for the workings of the human body. It was systemised in Ancient Greece, although its origins may go back further still. The theory was central to the teachings of Hippocrates and Galen and it became the dominant theory in Europe for many centuries. It remained a major influence on medical practice and teaching until well into the 1800s.

In this theory, humours existed as liquids within the body and were identified as blood, phlegm, black bile and yellow bile. These were in turn associated with the fundamental elements of air, water, earth and fire. It was further proposed that each of the humours was associated with a particular season of the year, during which too much of the corresponding humour could exist in the body – blood, for example, was associated with spring. A good balance between the four humours was essential to retain a healthy body and mind, as imbalance could result in disease. (Science Museum/Wellcome Library, London).