One crisp morning in 1794, John Dalton stood before the Manchester Literary and Philosophical Society and held up a small piece of ribbon. 'Is this ribbon red or pink?' he asked the audience. The room fell silent. Dalton saw a muddy brown, but everyone else saw a bright cherry red. That moment of confusion sparked a lifelong quest. Dalton, a quiet teacher and scientist, had just discovered that his own eyes saw the world differently from others. He didn't know it yet, but he was about to uncover a condition that would one day be called colour blindness.

Dalton was born in 1766 in a small village in England's Lake District. His family was poor, and he left school at age twelve to help on the farm. But John loved learning. He borrowed books from anyone who would lend them and taught himself mathematics, Latin, and science. By his late teens, he was teaching at a local school. He later moved to Manchester, where he became a tutor at a college. There, he began to study the weather, gases, and the nature of air. His careful observations and simple experiments earned him respect among scientists, even though he had no formal university degree.

The turning point came when Dalton started studying his own vision problem. He asked friends and family to describe colours, and he recorded their answers. He noticed that his brother also saw colours differently, which suggested the condition was inherited. Dalton collected data for years, testing dozens of people. He even asked his students to look at coloured ribbons and report what they saw. In 1798, he published a paper describing what he called 'colour blindness'—though he used the term 'daltonism' for many years. His work was the first scientific description of the condition.

His careful observations and simple experiments earned him respect among scientists, even though he had no formal university degree.

Dalton faced a challenge: many people laughed at his ideas. Some thought he was simply careless or that his eyes were weak. But Dalton did not give up. He continued his research, and he also made major discoveries in chemistry. He developed the atomic theory, which states that all matter is made of tiny particles called atoms. This idea changed science forever. Dalton's determination to understand his own difference helped him think carefully about how we observe the world. He once said, 'I do not consider it a defect, but a peculiarity.'

Dalton's work on colour blindness had a lasting impact. Today, about one in twelve men and one in two hundred women have some form of colour vision deficiency. Dalton's careful records helped doctors understand how the condition is passed down through families. A fun fact: after Dalton died in 1844, scientists examined his eyes and found that he had a rare form of colour blindness called deuteranopia. His preserved eyes are still kept in a museum in Manchester. John Dalton showed that a personal quirk could lead to a great scientific discovery.