"Interest has its justification in the right of property. If a man can claim the ownership of any kind of wealth, he is the owner of all it fairly produces.
Past labor has all the sacredness of present labor, and as justly claims its reward.
An associate in production, it is entitled to a share in the product. Whoever by labor produces wealth, and by self-denial preserves it, should be allowed all the benefit that wealth can render in future production.
This is the only condition upon which the largest accumulation of wealth can be secured; it presents the only motive that can withstand the impulse to immediate gratification.
The desire to gain and the desire to spend are both in human nature, and are conflicting passions. What one takes, the other must relinquish.
If, therefore, the desire to spend is unchecked, all wealth and physical well-being disappear in riot and wastefulness.
There is the further consideration, that, since to loan capital is to incur risk, that risk should be compensated." ~Amasa Walker, The Science of Wealth