John Calvin on Isaiah 28:6

6. And for a spirit of judgment. He explains the manner in which the Lord will adorn that “remnant” with additional splendor; for he holds out instances of the true art of civil government, which mainly contributes to the upholding of nations. It consists chiefly of two things, counsel and strength. The internal administration must be conducted by counsel and wisdom, and “strength” and force are needed against enemies who are without. Since therefore it is by these two defences that kingdoms and commonwealths defend and uphold their rank, he promises to his people the spirit of “wisdom” and “strength.” At the same time he shews that it is God who gives both, and that they ought not to be expected from any other; for magistrates will not be able to rule and to administer justice in a city, and military generals will not be able to repel enemies, unless the Lord shall direct them.