William Hetherington provides additional insight into the importance of Apollonius' contributions to the debates over church polity, History of the Westminster Assembly of Divines, pp. 301-302:
There appeared another work at this time, not indeed written by one of the Assembly of Divines, but so intimately connected with the controversies which were agitated among them, that it deserves to be mentioned here. This was a treatise written by the celebrated Apollonius of Middleburg, entitled, "Consideratio Quarundam Contraversiarum ad Regimen Ecclesiae Dei Spectantium, quae in Angliae Regno hodie Agitantur." When this treatise was published, a copy of it was sent to each member of the Westminster Assembly. "It was," says Baillie, "not only very well taken, but also, which is singular, and so far as I can remember, absque exemplo, it was ordered, nemine contradicente, to write a letter of thanks to Apollonius."1 The spirit of this work is thoroughly Presbyterian, encountering alike the theories of the Independents and the Erastians. It consists of seven chapters, each treating of a separate topic briefly, but with great clearness and force of reasoning. They are as follows: -- "1. Concerning the qualification of Church members. 2. Concerning a Church covenant. 3. Concerning the Church visible and instituted. 4. Concerning power ecclesiastical. 5. Concerning ecclesiastical ministry and its exercise. 6. Concerning Classes (Presbyteries) and Synods, and their authority. 7. Concerning forms or directories of faith and worship." It will at once be seen, that in the discussion of these topics the learned author must come into direct collision with both the Independents and the Erastians; yet his work has very little of a merely controversial character, being a calm and dispassionate, but very clear and able, disquisition concerning these important theological questions. There is another very valuable work by the same author, written a short time before the meeting of the Westminster Assembly, but treating very fully of the Erastian theory. Its title is, "Jus Majestatis Circa Sacra; sive, Tractatus, Theologicus de jure Magistratus circa res Ecclesiasticus." A translation of this work, for the purpose of general circulation, would be a very valuable contribution to the cause of religious liberty, which is at present beset by so many and such formidable enemies.
1 Baillie, vol. ii. p. 246.
It is to be hoped that one day someone will heed this encouragement from Hetherington to translate Jus Majestatis Circa Sacra. There are other works by Apollonius written in Dutch which this writer would very much like to see in English, such as Tractaat van eenige byzondere Deugden der Kinderen Gods (Treatise on some especial Virtues of the Children of God), and Over den Sabbath (On the Sabbath), both published in 1652. Apollonius is little-known in our day, but in the heady days of international Puritanism, his writings constituted a major Dutch contribution to the debates over church polity in Old and New England in defense of Presbyterianism.