The objective of this paper is the Arabic edition and the English translation of the Dissertation on thirst (الكلام في العطش), an anonymous text included in the miscellaneous manuscript nº 888 of the Royal Library of the Monastery of San Lorenzo de El Escorial in Madrid (Spain). This small treatise describes what thirst is, the types of thirst that exist, the causes why hydroponics are averse to water, the reason why diabetic people are continuously thirsty, the causes why people with fever are thirsty, the reason why some foods produce thirst and others do not, and so on. The whole manuscript is composed of fourteen works, written by the same copyist along 170 folios under the general title The book of medical and philosophical curiosities and utilities (كتاب النكت والثمار الطبية والفلسفية) and their subject are curious matters that are generally out of the span of most works on these two branches of knowledge.