Ishaq Ibn Imran, a physician in the city of Kairouan, in what is now Tunisia, produced a treatise on melancholy around AD 900. Omrani et al Reference Omrani, Holtzman, Akiskal and Nassir Ghaemi¹ say it is the oldest-known surviving manuscript dedicated entirely to melancholia that includes manic-depressive illness; it claims that melancholy could be due to hereditary and environmental influences and that ‘Melancholy affects the soul through fear and sadness – the worst thing that can befall it. Sadness is defined by the loss of what one loves; fear is the expectation of misfortune’. They conclude that ‘in many ways, our current views differ little from our medieval forebears’. Treatments comprise over half of the material.

Constantinus Africanus (AD 1015–1098) is one of the most influential medical scholars of the Middle Ages and a key figure in the revival of scientific medicine. In 1077, he arrived in Salerno, southeast of Naples, where he was linked with the Schola Medica Salernitana, the first European medical school. From Tunis, he brought manuscripts of the masters of Arabic medicine, which as a monk at Monte Cassino he translated and modified into an opus of Latin texts cited under his name. These circulated throughout Europe to the 17th century, laying the foundations for medical curricula. As an example of his reach, De Melancholia was copied at the priory of Kirkham, Yorkshire, in the mid-12th century. All that aside, Constantine is accused of plagiarism, and De Melancholia comprises parts of Ishaq Ibn Imran's treatise.

Constantine wrote De Melancholia because it was a malady prevalent ‘in these regions’: those intent on study and books of philosophy are especially liable to melancholy because of their scientific investigations, their tired memories and the failure of their minds, as are those who lose their beloved possessions, such as their children and dearest friends or some precious thing which cannot be restored. Many religious persons fall into this disease from their fear of God and contemplation of the Last Judgement: they become drunk, as it were, with excessive anxiety and vanity.

Treatments of contemporary charm include a magnetic mountain on the shore of the Indian Ocean that draws all the iron nails out of passing ships. Constantine recounts that Rufus of Ephesus says the magnet comforts those afflicted with melancholy and removes their fears and suspicions. Today, so it is claimed, transcranial magnetic stimulation uses magnetic fields to stimulate nerve cells in the brain to improve symptoms of depression.

Chaucer names Constantine in his Prologue to The Canterbury Tales (1387–1400) and in The Merchant's Tale as a source of aphrodisiacs: