'It was the spirit of Cathmor, stalking, large, a gleaming form. He sunk by the holllow stream, that roared between the hills -"
This image is based on a scene in Book VIII of 'Temora', one of the poems in the Ossianic cycle, first published by the Scottish poet James Macpherson in 1762. The scene is an engraving by William Angus, from a drawing by John Augustus Atkinson in a 1903 London edition of 'The Poems of Ossian'. Ossian is the narrator and purported author of the poems, which mainly cycle through a series of battles and heroics by various characters —including Ossian's father, Fingal.
The two figures in the forefront are Clonmal, an elderly druid, and Sulmalla, the daughter of the king of Inishuna. In the background, we see the ghostly figure of Cathmor. Being in love with Cathmor, Sulmalla had followed him to war: in turn, he had asked her to join Clonmal in the valley of Lona for the duration of a battle. Unfortunately, Cathmor dies killed at the hands of Fingal.
In the scene Cathmor appears as a spirit to Sulmalla, who immediately understands his misfortune.