VI. But the orthodox speak far differently. They affirm that there is a natural law, not arising from a voluntary contract or law of society, but from a divine obligation being impressed by God upon the conscience of man in his very creation, on which the difference between right and wrong is founded and which contains the practical principles of immovable truth (such as: “God should be worshiped,” “parents honored,” “we should live virtuously,” “injure no one,” “do to others what we would wish them to do to us” and the like). Also that so many remains and evidences of this law are still left in our nature (although it has been in different ways corrupted and obscured by sin) that there is no mortal who cannot feel its force either more or less. Now they wish this law to be called natural, not because it has its origin from bare nature (since it depends upon God the supreme lawgiver), but because it becomes known from the aspect of creatures and the relation of man to God, and the knowledge of it is impressed upon the mind by nature, not acquired by tradition or instruction. [Francis Turretin, Institutes of Elenctic Theology, 2.11.I.7]
VIII. Thus the origin and foundation of this law ought not to be sought (as the Jews falsely seek it) from “the seven precepts” which they maintain were given to Adam and Noah …
IX. But it must be drawn from the right of nature itself, founded both on the nature of God, the Creator (who by his holiness must prescribe to his creatures the duties founded upon that right), and on the condition of rational creatures themselves (who, on account of their necessary dependence upon God in the genus of morals, no less than in the genus of being, are bound to perform or avoid those things which sound reason and the dictates of conscience enjoin upon them to do or avoid)
X. The right of nature … strictly and properly for that which has reference only to rational creatures. The lawyers include this under the laws of nations. It is rightly described by common practical notions, or the light and dictation of conscience ..[Ibid., 2.11.I.8-10]
XXII. If it is asked how this natural law agrees with or differs from the moral law, the answer is easy. It agrees as to substance and with regard to principles, but differs as to accidents and with regard to conclusions. … [Ibid., 2.11.I.22]
Looks like Turretin is far from a Neo-Kuyperian on the issue of natural law.