In medical theory, al-Razi relied mainly on Galen, but his particular attention to the individual case, stressing that each patient must be treated individually, and his emphasis on hygiene and diet reflect the ideas and concepts of the empirical hippocratic school. Rhazes considered the influence of the climate and the season on health and well-being, he took care that there was always clean air and an appropriate temperature in the patients' rooms, and recognized the value of prevention as well as the need for a careful diagnosis and prognosis.