According to the authors of Keulemans' biography Feathers to Brush, the artist's interest in spiritualism began with a premonition of his son Isidore's death.
 In an article in the Bristol Mercury and Daily Post of March 3, 1883, Keulemans tells how he and his family were living in Paris in December 1880 when there was an outbreak of smallpox.
 The parents sent three of their children to London to live with their grandparents; one of the children was his favorite son Isidore, aged four.
In the morning of 24 January 1881, Keulemans woke up and heard Isidore's voice and saw his face.
The apparition returned the next day, which made Keulemans very uneasy.
A few days later he received a letter from London to tell him Isidore was ill, when in fact he had died exactly on the day of the first appearance of Isidore in John Gerrard's dream.

Subsequently, Keulemans experienced further incidents increasing his belief in the supernatural, in particular which he claimed could be awakened via the painting of a bird's eye.
Keulemans began an association with the Society for Psychical Research; later he became disenchanted with the prevalence of fraud in spiritualist society, and used his scientific training to expose the trickery he saw performed by mediums.

Keulemans claimed to have visited nearly 400 seances and gave some examples of the alleged trickery in support of his criticisms.
He seems not to have been opposed to Spiritualism in its philosophical or metaphysical bases, but against its pretensions as a science based on demonstrable fact.
According to the authors of Keulemans' biography Feathers to Brush, the artist's interest in spiritualism began with a premonition of his son Isidore's death.  In an article in the Bristol Mercury and Daily Post of March 3, 1883, Keulemans tells how he and his family were living in Paris in December 1880 when there was an outbreak of smallpox.  The parents sent three of their children to London to live with their grandparents; one of the children was his favorite son Isidore, aged four. In the morning of 24 January 1881, Keulemans woke up and heard Isidore's voice and saw his face. The apparition returned the next day, which made Keulemans very uneasy. A few days later he received a letter from London to tell him Isidore was ill, when in fact he had died exactly on the day of the first appearance of Isidore in John Gerrard's dream.
Subsequently, Keulemans experienced further incidents increasing his belief in the supernatural, in particular which he claimed could be awakened via the painting of a bird's eye. Keulemans began an association with the Society for Psychical Research; later he became disenchanted with the prevalence of fraud in spiritualist society, and used his scientific training to expose the trickery he saw performed by mediums.
Keulemans claimed to have visited nearly 400 seances and gave some examples of the alleged trickery in support of his criticisms. He seems not to have been opposed to Spiritualism in its philosophical or metaphysical bases, but against its pretensions as a science based on demonstrable fact.
John Gerrard Keulemans