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.^[1]

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He describes there the original innovation of applying mathematics to pharmacology and specifically the quantification of the effect of drugs. For example, he developed a mathematical scale to quantify the strength of drugs. Al-Kindi was the first one who tried to use a serious quantification in medicine.^[2]

He developed a mathematical scale to quantify the strength of a drug, and a system, based the phases of the Moon, that would allow a doctor to determine in advance the most critical days of a patient's illness.^[3]

During the Arabic-Latin translation movement of the 12th century, De Gradibus was translated into Latin by Gerard of Cremona.^[1] Due to the complex mathematical reasoning employed in the book, many early European physicians initially had difficulty in interpreting his quantification of drug strength, such as Roger Bacon who wrote the following commentary:^[4]

"The degree [of a compound] can only be determined by the method taught by Al-Kindi’s De gradibus, one extremely difficult and almost entirely unknown among Latin physicians of these days, as everyone is aware. Whoever wants to become perfect in this philosopher’s art must know the fundamentals of mathematics, because the species of greater and lesser inequality, the species of ratios, and the very difficult rules of fractions are all used by this author."

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