I've recently re-read William Ames' short treatise on the encyclopedia of knowledge, entitled Technometry. William Ames was a Puritan whose influence was great both on the Continent, but especially in the American colonies, where his Marrow of Theology became THE systematic theology text of the New England Puritans. The Technometry is a special treatise for two reasons: 1) It was the last work that Ames sought to complete his system of thought, and 2) as such it stands as Ames' definitive view on the relation and purpose of knowledge as pursued by the liberal arts.
The relevance of Ames to the two-kingdom debate comes in his discussion of the placement of certain topics of study under the more general classifications of art. Ames begins by defining art as "the idea of eupraxia or good action, methodically delineated by universal rules." Eupraxia is, for God, one unique and simple act, but is manifold and divided in the perception of human reason (thesis 15). After several more necessary distinctions, Ames arrives at teleology of the arts, which he identifies as the glory of God (thesis 60). The understanding of the created order was perfect prior to the fall, in which it was made obscure, but is once more rendered clear in the Scriptures (theses 61-62). He goes on to discuss the virtues of pagan writing, and concludes: "With the exception of goodness, the type of things still conveys perfectly enough the remaining principles; but these remaining principles are to be inwardly seen and gathered only by those penetrating by untiring analysis the inner aspects of type" (thesis 66). The upshot of this section is that perception of the principles governing the natural world is possible by investigation of their inherent properties (i.e. their God-given natures), excepting the perception of goodness. This thesis destroys all confidence in the natural law, insofar as the natural law is supposed to perceive what is the good for man before God and within society. Ames continues in his discussion of pagan study of nature and draws several conclusions, one of which is, "that in theology and jurisprudence. . .the opinions of Christians are to be adhered to rather than those of the impious, even when very many" (thesis 76) and clarifies this statement in the next thesis by saying that Plato and Aristotle are good testing grounds, but only in subjection to truth, which he has already annexed to Scripture.
When Ames does get to discussion the liberal arts, he identifies six (dialectic, grammar, rhetoric, theology, mathematics, physics). In discussing theology, it is immediately apparent the great extent to which it governs all the others arts. "Theology alone homogeneously transmits (2) the universal teaching of virtues (i.e., of honesty, law, and equity). Theology alone homogeneously delivers the whole revealed will of God for directing our morals, will, and life. This whole revealed will of God alone is that right reason--if absolute rectitude be looked toward, as it must be looked toward here--in which alone, by the consensus of all who are of sound mind, the norm or rule of honesty, law, and equity (and therefore of virtues) is constituted" (thesis 113). As if this wasn't a clear enough statement that just laws are derived from Scripture, Ames follows in thesis 114 with, "Therefore, although there may be some usefulness and necessity of household economy and politics for jurisprudence, the principal usefulness and necessity is nevertheless theology's. Theology abundantly supplies most distinctly and most perfectly the general rules, the first principles, and all the foundations of law; household economy and politics convey to jurisprudence only some general rules and first principles that have been accommodated to their own uses."
Then Ames moves into an attack on what may be called the proto R2KT advocates. Thesis 115 says, "There is clearly no usefulness and necessity of ethics for jurisprudence. For ethics may properly contain nothing except imperfection, while all the remaining things have been borrowed from theology." Continuing in 116 with refutations of of ethicists:
"Notwithstanding, the pretexts of the ethicists have thus now been often rewoven. The principal pretexts of the ethicists are as follows. (1) They distinguish civil and moral happiness from supernatural and eternal happiness. Nevertheless, (a) supernatural and eternal happiness, considered with respect to the civil and political society in which we live, is civil and moral. (b) That which they call civil and moral (in contradistinction to that which is supernatural) ought not deservedly to be called "natural," that is, that which proceeds from corrupted nature, but rather "above nature," flowing from those vestiges of the integral state that remain through divine grace and have also been established and increased in a certain manner in the wiser pagans. (c) The proper good, the happiness or end of man, is not manifold. (d) That is not true virtue that may not lead man to his end and highest good. (2) They say that the object of theology is the inner man and piety, while the object of ethics is external morals and uprightness (probitatem). Nevertheless, external morals and uprightness are equally the object of theology, which commands external as much as internal obedience, as Keckermann also acknowledges in canon 10, "Concerning the End of Ethics," in General Precognitions of the System of Ethics. Ethics, no less that theology, claims for itself, the reform of man according to the image of God by prescribing the precepts of virtues and by calling away from vices. This is why prudence does not refuse to hear of ruling the will and appetite. (3) They add to that ethical virtues are confined to the limits of this life, while theological virtues are extended to the future life. But first, if something should therefore immediately cease to be theological because it is confined to the limits of this life, many things that are truly theological would cease to be theological, such as the preaching of the Word, the administration of the sacraments, etc. Secondly, they will never be able to prove that any virtue in its essence is about to cease with this life, although in some particular individuals the likenesses of certain virtues may be about to cease. (4) They say that the subject of ethics is the upright, good, and honest man; while the subject of theology is the religious and pious man. That which has been said with respect to the second reason above applies here also. And they respond otherwise with respect to the first part of this assertion when they affirm that ethics teaches to live piously. With respect to the latter part of this assertion, according to Titus 2:12, Paul manifestly says that theology also teaches to live temperately and justly, that is, uprightly and honestly. (5) The difference between ethical and theological virtues is excellently set forth in Matthew 5:20 and also in chapters 6 and 7. Nothing appears in these texts except that, for the sake of virtue, no one ought to propose for himself private usefulness and glory but honesty alone. Likewise, more than has been recognized, that which the ethicists say about their virtues also appears here. For they are unwilling that freedom, riches, honors, and health are regarded by their ethicist only to the extent that they are a help and instrument for exercising more conveniently and more easily the actions of virtue. But if ethics should transmit hypocrisy and pharisaism, of what further mention is made here, who, I ask, will be its auditor? The difference between ethical and theological virtues is excellently set forth secondly according to Romans 1 and 2. Nothing ethical is considered here, unless perhaps they wish the ethicist to communicate the catalogue of vices at the end of the first chapter. But by means of what front? The purpose (scopus) of the apostle elsewhere in these two chapters is to make it clear that all men are transgressors of the divine law and thus deserters of theological virtues."
Ethicists here is referring to those in the church who were followers of Aristotle, the philosopher who put a great deal of emphasis upon politics as the supreme practical science. In other words, Aristotle is the grandfather of natural law theory, and his Christian follows sought to carve out a non-theological realm of ethical principles and norms for directing law and society. To put the cap on Ames' position, one needs only to understand what he means by jurisprudence: "The higher faculties are as follows. . .the juridical, for proclaiming law and administering justice" (thesis 123).
For Ames, as for any consistent Reformed position, the lower faculties of politics, law, medicine, etc. all find their governing principles and purposes in theology, and theology as it is primarily revealed in the Scriptures (containing the truths by which the order of God revealed in creation may be properly discerned).