This, indeed, is the characteristic feature of our times.

It has produced a great revolution in national policy.
In former ages wars were made for the procuring of slaves.

A conqueror transported entire populations, and extorted from them forced labor, for it was only by human labor that human labor could be relieved.

But when it was discovered that physical agents and mechanical combinations could be employed to incomparably greater advantage, public policy underwent a change; when it was recognized that the application of a new principle, or the invention of a new machine, was better than the acquisition of an additional slave, peace became preferable to war.

And not only so, but nations possessing great slave or serf populations, as was the care in America and Russia, found that considerations of humanity were supported by considerations of interest, and set their bondmen free.
SCIENTIFIC INVENTIONS.