P.T. Barnum wrote "The Art of Money Getting: The Golden Rules for Making Money" in 1880 at the age of 70 when he was already an accomplished businessman, politician, philanthropist, and author--after his hugely successful 1855 autobiography "The Life of P.T. Barnum: Written By Himself."
It's available online at http://www.gutenberg.org/ebooks/8581
This post provides a summary of the 21 rules and some commentary for today's entrepreneurs. Barnum's Advice Holds Up Well after Thirteen Decades
What was most surprising about reading his "Golden Rules For Making Money" was how timeless they were. The hold up very well 140 years later.
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