Alchemist Hennig Brand accidentally discovered the chemical element phosphorus while searching for the "philosopher's stone", a substance that was believed to transmute base metals into gold.
Like other alchemists of the time, Brand searched for the "philosopher's stone", a substance that supposedly transformed base metals (like lead) into gold. By the time his first wife died, he had exhausted her money on this pursuit. He then married his second wife Margaretha, a wealthy widow whose financial resources allowed him to continue the search.
Like many before him, he was interested in water and tried combining it with various other materials, in hundreds of combinations. He had seen for instance a recipe in a book 400 Auserlensene Chemische Process by F. T. Kessler of Strasbourg for using alum, saltpeter (potassium nitrate), and concentrated urine to turn base metals into silver.
Around 1669 he heated residues from boiled-down urine on his furnace until the retort was red hot, where all of a sudden glowing fumes filled it and liquid dripped out, bursting into flames. He could catch the liquid in a jar and cover it, where it solidified and continued to give off a pale-green glow. What he collected was phosphorus, which he named from the Greek word for "light-bearing" or "light-bearer."
Phosphorus must have been awe-inspiring to an alchemist: it was a product of man, and seeming to glow with a "life force" that did not diminish over time (and did not need re-exposure to light like the previously discovered Bologna Stone). Brand kept his discovery secret, as alchemists of the time did, and worked with the phosphorus trying unsuccessfully to use it to produce gold.