P.T. Barnum penned "The Art of Money Getting" in 1880 after building America's most famous museum and co-founding Barnum & Bailey Circus. At age 70, Barnum distilled his lifetime of hustle into 20 straightforward rules for financial success. His core philosophy centers on finding work that matches natural abilities rather than chasing whatever pays bills.

Barnum's first rule emphasizes choosing a vocation aligned with personal strengths, arguing most people get this backwards. He warns against debt as freedom-killing, advocating instead for keeping income above expenses. His third principle demands full commitment to whatever work you choose—half-effort leads to poverty while thoroughness creates wealth.

The fourth rule stresses integrity preservation, noting customers avoid merchants they distrust. Barnum observed that dishonesty might yield short-term gains but destroys long-term reputation. These principles emerged from personal experience, including bankruptcy from a Connecticut clock company investment and subsequent recovery.

Cool Tools Lab publishes this historical advice through their Book Freak newsletter, alongside other tools-focused publications. Barnum's century-old wisdom remains relevant for modern entrepreneurs seeking practical financial guidance.