The purpose of this book is to present the positive scientists of the Byzantine Era to the general readership, as well as to scholars of the History of the positive sciences. By positive scientists we mean precisely those mathematicians, astronomers, alchemists, natural philosophers, naturalists, engineers, geographers, mineralogists, architects, pharmacologists, zoologists, botanists, and agronomists who have somehow learned their science and then practiced it, while several from them they taught it and presented it in writing.