Galen and Avicenna are against this, for Avicenna says there are but three simple fevers, a fever from phlegm, one from choler and one from sanguine humour; for when it (the blood) corrupts, it causes not a simple fever, but a compound fever; for the blood is moderate, and when it heats and putrefies, the thinner part turns to choler, and the thicker to melancholy. Avicenna11 says he found much [adverse] criticism regarding this saying of Galen's, and says [moreover] that sanguine humour generates one simple fever only. I say with regard to this briefly: if vapour arise on account of the