Arthur Stace, better known as Mr Eternity, converted to Christianity in 1930. Inspired by evangelist John Ridley's words "Where will you spend Eternity?", he found himself writing the word in chalk across Sydney.
It was estimated that he wrote the word about 500,000 times over 35 years. Today, there is only one surviving "Eternity", inside the bell in the Sydney General Post Office clock tower.
As we enter the Christmas season, one wonders what Stace would have made of Sydney's increasing secularisation, with the 2016 census finding 43.8 per cent of city's residents declaring no religion.
Depending on one's point of view, this is either a grim reminder of the decline of society, or a triumph of intellectual progression.
At the end of the 19th century, it was the French neurologist Jean Charcot and his pupil Sigmund Freud who first described religion as conducive to hysteria and neurosis.
However, there are very real benefits to Christmas. What has been well documented is that religious practices that have a social component have a powerful, and usually beneficial, impact on the individual.
As for the concept of Eternity itself, religious observances may still have a role in a secular world, but notions such as the afterlife are losing currency.
Christmas is a time of sharing, of tradition, of being close to each other.
Eternity is about considering the possibility of a fundamental cosmic truth.
Both are concepts that have often been thought to be inextricably linked to specific religious dogma.
Perhaps it is time to acknowledge them both as intact entities with their own existence, and relevance to a broader concept – who we are as human beings. Past, present, and future.
Dr Neil Jeyasingam is a psychogeriatrician at the University of Sydney.