The objective of the study is to discuss the question, "how did physicians come to grasp some facts in the absence of scientific experimentation and medical technology?" within the framework of examples from Ahı? Ahmed Çelebi's fifteenth century Turkish treatise on the urinary calculus. Çelebi's monograph on the urinary calculus in the kidneys and the bladder written in Turkish in Arabic alphabet is transliterated and studied within the framework of the medical theory of the period. The sample information for this study was randomly chosen. Examples of epidemiological information, diets against urinary calculus formation, diagnoses of kidney and urinary bladder calculi, and symptomatic therapies noted in Çelebi's treatise are discussed, with results briefly compared with today's data. The study of Çelebi's treatise shows that it was possible to reach some medical facts with the methods of the period.