Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Of the Arabic school Rhazes was the first to speak of light as a help in disease. He died 932 A. D. Avicenna, who followed him in the eleventh century, and Albucasis in the twelfth, touch but slightly upon light as a therapeutic measure.