Yule is believed to have borrowed the phrase from Sir Henry Rider Haggard's fantasy novel "The People of the Mist" (1894). The first chapter includes the sentence: "To his right were two stately gates of iron fantastically wrought, supported by stone pillars on whose summit stood griffins of black marble embracing coats of arms and banners inscribed with the device 'Per Ardua ad Astra. It is possible that Rider Haggard had taken it from the Irish family of Mulvany, who had used it as their family motto for centuries, translating it as "Through Struggles to the Stars".