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 the mathematicians, astronomers, alchemists, natural philosophers, naturalists, engineers, geographers, mineralogists, architects, pharmacologists, zoologists, botanists, and agriculturists who in some way learned their science and then practiced it, while several of they taught it and presented it in writing.