society thus
constituted from the beginning it has proved possible to build up
our Federal Union, in which the states, while for certain purposes
indissolubly united, at the same time for many other purposes retain
their self-government intact. As in the case of other aggregates, the
nature of the American political aggregate has been determined by the
nature of its political units.

[Sidenote: Vastness of the functions retained by the states in the
American Union.]
_Secondly_, let us observe how great are the functions retained
by our states under the conditions of our Federal Union. The
powers granted to our federal government, such as the control over
international questions, war and peace, the military forces, the
coinage, patents and copyrights, and the regulation of commerce
between the states and with foreign countries,--all these are powers
relating to matters that affect all the states, but could not be
regulated harmoniously by the separate action of the states. In order
the more completely to debar the states from meddling with such
matters, they are expressly prohibited from entering into agreements
with each other or with a foreign power; they cannot engage in war,
save in case of actual invasion or such imminent danger as admits of
no delay; without consent of Congress they cannot keep a military or
naval force in time of peace, or impose custom-house duties. Besides
all this they are prohibited from granting titles of nobility, coining
money, emitting bills of credit, making anything but gold and silver
coin a tender in payment of debts, passing bills of attainder, _ex
post facto_ laws, or laws impairing the obligation of contracts.
The force of these latter restrictions will be explained hereafter.
Such are the limitations of sovereignty imposed upon the states within
the Federal Union.

Compared with the vast prerogatives of the state legislatures, these
limitations seem small enough. All the civil and religious rights
of our citizens depend upon state legislation; the education of the
people is in the care of the states; with them rests the regulation
of the suffrage; they prescribe the rules of marriage, the legal
relations of husband and wife, of parent and child; they determine the
powers of masters over servants and the whole law of principal and
agent, which is so vital a matter in all business transactions; they
regulate partnership, debt and credit, insurance; they constitute all
corporatio