de gradibus de gradibus de gradibus was an arabic book published by the arab physician al-kindi (c. 801–873 ce). de gradibus is the latinized name of the book. an alternative name for the book was quia primos. authoral-kindioriginal titleرسالة في قدر منفعة صناعة الطب in de gradibus, al-kindi attempts to apply mathematics to pharmacology by quantifying the strength of drugs. according to prioreschi, this was the first attempt at serious quantification in medicine. he also developed a system, based on the phases of the moon, that would allow a doctor to determine in advance the most critical days of a patient's illness. during the arabic-latin translation movement of the 12th century, de gradibus was translated into latin by gerard of cremona. al-kindi's mathematical reasoning was complex and hard to follow; roger bacon commented that his method of computing the strength of a drug was extremely difficult to use.