The Greek original of Galen's is lost, nor has a copy of the complete translation into Arabic, made by Hunayn b. Ishāq in the first half of the ninth century, come down to us, though some passages of it are quoted by various Arab authors. A summary of the translation, however, was discovered by P. Kraus in a miscellaneous manuscript in Cairo and published by him in the Bulletin of the Faculty of Arts of the University of Egypt, vol. v/i.