 In late antiquity, medical writing veered increasingly in the direction of the theoretical at the expense of the practical, with many authors merely debating Galenism.Magnus of Nisibis was a pure theorist, as were John of Alexandria and Agnellus of Ravenna with their lectures on Galen's "De Sectis".So strong was Galenism that other authors such as Hippocrates began to be seen through a Galenic lens, while his opponents became marginalised and other medical sects such as Asclepiadism slowly disappeared.