An investment in knowledge pays the best interest.

The line treats education and learning as capital: time, effort, and money spent on acquiring knowledge yield returns that compound over a lifetime. “Best interest” works as a pun—both the highest advantage and the highest financial interest—suggesting that intellectual growth outperforms purely monetary investments because it improves judgment, adaptability, and opportunity. In Franklin’s pragmatic moral universe, knowledge is not merely ornamental; it is a tool for personal advancement and public benefit. The aphorism also implies that knowledge is durable wealth: unlike material assets, it cannot be easily taken away and can generate further gains through better decisions and innovation.

1) “An investment in knowledge always pays the best interest.”
2) “Investing in knowledge pays the best interest.”