I’m a great believer in luck, and I find the harder I work the more I have of it.I like the sentiment and I suspect it masks a profound truth - That the harder you work, the more likely you are to place yourself in the position of taking advantage of auspicious opportunities.
That said though, this just didn't sound like anything I had ever read by Jefferson. Turning to Quote Investigator, it turns out that my sense of something being off was correct.
The saying has been ascribed to Jefferson for a few decades. However, the valuable Thomas Jefferson Monticello website states that there is no evidence to support the attribution [TJGB]:I like the fake Jefferson quote better but "Diligence is the mother of good luck" will do.
Neither this statement nor any variations thereof have ever been found in Thomas Jefferson’s writings.The earliest appearance of this aphorism known to QI is in a 1922 collection titled “Listen to This” by Coleman Cox who composed a large number of sayings. This book was a successor to a collection titled “Take It From Me” by Cox. The copy of “Listen to This” at the HathiTrust repository has gold lettering on the cover stating that it was gift to the industrialist Henry Ford [CCGB]:
I am a great believer in luck. The harder I work, the more of it I seem to have.This theme has been reflected in adages for quite a long time. The Oxford Dictionary of Quotations lists the following proverb which it dates to the late 16th century [OXDL]:
Diligence is the mother of good luck.