It takes the bayonet to prevent them; hence, it is wrong to prevent them.
In this second part, Frédéric Bastiat shows how diversity (which he call natural inequalities) distributes the various positions within an economy. The comparative advantages are often linked to natural agents, which are spread over the globe unevenly. Depending on the circumstances, it would be possible to demand monopoly prices but competition is the phenomenon that will allow to break the monopolies.
Today’s quote is referring to international protectionism that seeks to suppress or at least limit competition from abroad, which is what Frédéric Bastiat fought all his life. After explaining why forbidding foreign competition is a way to shoot oneself in the foot, he concludes with the following hefty argument that applis to numerous decisions imposed by government, viz. that a reasonable policy will be supported by the population without having to impose it on them by force.