Around 1875, when Anthony was a student at St. Gall boarding school, he developed a serum for exploring the Veil. He and the other members of the Science and Philosophy Club injected themselves with serum, entered the Veil and encountered the Simurg. In 1876, the school abruptly closed, perhaps as a result of their actions.
Devitt and his friends speculated that St. Gall closed because of Father Ernest's strange behavior, which probably resulted from their encounter with the Custodian.It is unclear whether The Playwright continued to use Anthony's serum, or if they used a different means for exploring the Veil.
In the late 1880s, Alexandre and a colleague (probably Anthony) developed a more powerful serum. Alexandre's colleague located a chemical formula in a treatise that was written by Lully Raymundus in the 12th century. Raymundus called the formula "Hoopoe" after a legendary bird that guided other birds away from a land of mists. When the colleague experimented with the serum, he remarked that it seemed to cause brain death. Alexandre apparently took the serum in 1887 and remained in a deep trance until at least 1891.
When Devitt investigated St. Gall, he found evidence that patients had been injected with serum.
When Devitt found Alexandre in 1892, he seemed to be in a trance, even though there were also signs that he could take care of himself. Eventually, Alexandre regained consciousness. At Devitt's request, he injected Devitt with serum. Devitt had a series of disturbing visions and eventually found himself standing next to Alexandre in a land of mists. Together, they went off in search of the Last Door.