JACINTH (or HYACINTH). A gem, a variety of zircon. In the Middle Ages (q.v.), it was believed to avert depression. Marbodius ( 1037-1125), bishop of Rennes, wrote that it dispelled sadness and "vain suspicions'' (paranoia [q.v.]). Albertus Magnus (q.v.), in his Book of Secrets, wrote that "it maketh strangers sure, and acceptable to their guests. And it provoketh sleep for the coldness of it."
See alsoPRECIOUS STONES.
Bibliography: Evans J. 1922. Magical jewels.
JACKSON, JOHN HUGHLINGS (1835-1911). One of the most important British neurologists. His work was greatly influenced by Charles Brown-Sequard (q.v.). Jackson's early education left him without a classical background or an appreciation of the arts, and his reading was limited to thrillers and Westerns, which he tore into two parts, and carried in his jacket pockets. As soon as each page was read, it was discarded. If he borrowed a book, he was likely to return it with the relevant pages torn out. Because he was a poor speaker and a poor writer, his ideas were slow to be recognized but eventually greatly influenced his followers. In 1862 Jackson joined the staff of the newly founded National Hospital for the Paralysed and Epileptic in Queen Square, London. In 1865 he married his cousin, Elizabeth Dade, who died in 1876 of cerebral thrombophlebitis, which caused frequent focal seizures. This particular type of epilepsy (q.v.) was first described by him and now is known as Jacksonian epilepsy. The death of his wife left him inconsolable, and for the remainder of his life he kept her place set at the dinner table. His last years were made more lonely by deafness. He became vague and absentminded and suffered from vertigo. The concept of levels