Einstein Left Words of Wisdom on Tokyo Hotel Stationery

The letters will go on sale later this month, and will be sold to the highest bidder. MENAHEM KAHANA/AFP/Getty Images

Einstein's long-lost secrets to happiness finally have resurfaced after being hidden away for nearly 100 years. The secrets were scribbled on two notes given to a Tokyo courier in 1922, and offer insight into the inner workings of one of the greatest minds to ever live.

Ninety-five years ago, famed physicist Albert Einstein wrote down (in German) two of his own personal theories on happiness. The first, written on hotel stationery, read: "A quiet and modest life brings more joy than a pursuit of success bound with constant unrest." The second, written on plain white paper, stated: "Where there's a will, there's a way," Express wrote.

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According to the backstory, relayed by the seller, Einstein gave the messages to a courier who had delivered Einstein a message while he was staying at the Imperial Hotel in Tokyo in 1922. Einstein gave the courier these notes rather than a monetary tip, the Daily Mail reported. "Maybe if you're lucky those notes will become much more valuable than just a regular tip," Einstein reportedly told the courier.

Einstein's premonition was accurate. Today, the notes are on auction in Jerusalem by the seller, who is a relative of the courier and wants to remain anonymous. They will go up for sale this Halloween, along with two other letters Einstein wrote in later years, according to IFL Science.

Related: Albert Einstein: A driven, curious and innovative mind that changed the course of history

The notes are especially valuable considering the date they were written: 1922. This was shortly after Einstein had been awarded the Nobel Prize for physics and had just begun to become a household name. Einstein was awarded the Nobel in 1921 for "his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect." However, he did not physically receive his award until a year later in 1922.

The law of the photoelectric effect proposed that light is both a wave and a particle, an understanding that soon became fundamental to quantum mechanics; without it we would have no solar cells.

There's no way of knowing what went through Einstein's mind as he wrote these notes, or what spurred his musings on happiness. Roni Grosz, an archivist in charge of the world's largest Einstein collection at Jerusalem's Hebrew University, told AFP the notes simply offer a "stone in the mosaic" of Einstein's portrait during a time when he had reached newfound fame.