In Pierce v. Society of Sisters, 268 U.S. 510 (1925) the US SC ruled:
Under the doctrine of Meyer v. Nebraska, 262 U.S. 390 , 43 S. Ct. 625, 29 A. L. R. 1146, we think it entirely plain that the Act of 1922 unreasonably interferes with the liberty of parents and guardians to direct the upbringing and education of children under their control. As often heretofore pointed out, rights guaranteed by the Constitution may not be abridged by legislation which has no reasonable relation to some purpose within the competency of the state. The fundamental theory of liberty upon which all governments in this Union repose excludes any general power of the state to standardize its children by forcing them to accept instruction from public teachers only. The child is not the mere creature of the state; those who nurture him and direct his destiny have the right, coupled with the high duty, to recognize and prepare him for additional obligations.
The phrase creature of the state is a legal term of art, used consistently in court opinions. A "municipality" and a "school district" are creatures of the state, as is a "corporation" or "body politic." These entities were created and devised by human laws for the purposes and benefit of society and government. The state can grant or withdraw certain powers and privileges as it sees fit.
Creatures of the state are "artificial" persons created in law, as contrasted with "natural" persons created by nature or God.