On October 16, 1843, Irish mathematician William Rowan Hamilton had a groundbreaking epiphany while walking along Dublin’s Royal Canal. Excitedly, he carved his discovery onto Broome Bridge with his penknife, creating the most famous graffiti in mathematical history. This seemingly simple inscription, ‘i² = j² = k² = ijk = -1’, revolutionized how mathematicians represent information and led to countless technical applications, from bridge design to search engine algorithms.