"Another not unimportant consideration is, that the powers of the general government will be, and indeed must be, principally employed upon external objects, such as war, peace, negotiations with foreign powers, and foreign commerce. In its internal operations it can touch but few objects, except to introduce regulations beneficial to the commerce, intercourse, and other relations, between the states, and to lay taxes for the common good. The powers of the states, on the other hand, extend to all objects, which, in the ordinary course of affairs, concern the lives, and liberties, and property of the people, and the internal order, improvement, and prosperity of the state."

-- Joseph Story, Commentaries on the Constitution, 1833

 
 
 
 
"This balance between the National and State governments ought to be dwelt on with peculiar attention, as it is of the utmost importance. It forms a double security to the people. If one encroaches on their rights they will find a powerful protection in the other. Indeed, they will both be prevented from overpassing their constitutional limits by a certain rivalship, which will ever subsist between them."

-- Alexander Hamilton, speech to the New York Ratifying Convention, 1788

 
 
"No human law can abolish the natural and original right of marriage, nor in any way limit the chief and principal purpose of marriage ordained by God's authority from the beginning: "Increase and multiply." Hence we have the family, the "society" of a man's house -- a society very small, one must admit, but none the less a true society, and one older than any State. Consequently, it has rights and duties peculiar to itself which are quite independent of the State."

-- Leo XII Rerum Novarum, (12), MAY 15, 1891