A pot of urine can tell a lot about your diet and health. It can tell whether you are adequately hydrated, or how well your kidneys are functioning. It can tell if you are suffering from jaundice, or if you have high blood sugar. Modern chemical analysis of urine can reveal a wide range of afflictions. Even centuries ago, before such diagnostic tests became available, and before there were microscopes and blood tests and X-rays, urine was the one and only body fluid that could be reliably analyzed. It was transparent, had different colors and sediments. It had a unique smell, and it could even be tasted.
A Doctor Examining Urine, by Trophime Bigot (1579–1650)