Which centers in his single person that can act with a vigor proportionate to such a vast dominion

“Russia is a European state,” she declared, meaning with this statement to eliminate the Russian’s traditional sense of geographical and cultural isolation, as well as the disdain of Europeans who believed that Russia was only a remote, primitive backwater. From there, she moved directly to an explanation of the need for absolutism in Russia. The sovereign was absolute, she said,“for there is no authority but that which centers in his single person that can act with a vigor proportionate to such a vast dominion.” Any other form of government risked weakness.

Could anyone rephrase or interpret the sentence in blue in an easier way?

Does that mean the authority should center on a single person, in other word the monarch, who can have the total power porportinate to this big terrority?

Thanks!