6. No marginal notes at all to be affixed, but only for the explanation of the Hebrew or Greek words, which cannot, without some circumlocution, so briefly and fitly be expressed, in the text.7. Such quotations of places to be marginally set down as shall serve for the fit reference of one Scripture to another.
Here's the section from the translators' preface that is relevant to the question (all emphases added are my own, and the original italics are omitted, also I'm working from a modernized adaptation of the letter in the preface):
Reasons moving us to set diversity of senses in the margin, where there is great probability for each
Some peradventure would have no variety of senses to be set in the margin, lest the authority of the Scriptures for deciding of controversies by that show of uncertainty should somewhat be shaken. But we hold their judgment not to be so sound in this point. For though "whatsoever things are necessary are manifest," as St. Chrysostom saith, and as St. Augustine, "In those things that are plainly set down in the Scriptures, all such matters are found that concern faith, hope, and charity" ; yet for all that it cannot be dissembled, that partly to exercise and whet our wits, partly to wean the curious from the loathing of them for their everywhere plainness, partly also to stir up our devotion to crave the assistance of God's Spirit by prayer, and lastly, that we might be forward to seek aid of our brethren by conference, and never scorn those that be not in all respects so complete as they should be, being to seek in many things ourselves, it hath pleased God in His divine providence, here and there to scatter words and sentences of that difficulty and doubtfulness, not in doctrinal points that concern salvation (for in such it hath been vouched that the Scriptures are plain), but in matters of less moment, that fearfulness would better beseem us than confidence, and if we will resolve upon modesty with St. Augustine (though not in this same case altogether, yet upon the same ground), Melius est dubitare de occultis, quam litigare de incertis, --"it is better to make doubt of those things which are secret, than to strive about those things that are uncertain." There be many words in the Scriptures which be never found there but once (having neither brother nor neighbor, as the Hebrews speak), so that we cannot be holpen by conference of places. Again, there be many rare names of certain birds, beasts and precious stones, etc., concerning which the Hebrews themselves are so divided among themselves for judgment, that they may seem to have defined this or that rather because they would say something than because they were sure of that which they said, as St. Jerome somewhere saith of the Septuagint. Now in such a case, doth not a margin do well to admonish the reader to seek further, and not to conclude or dogmatize upon this or that peremptorily? For as it is a fault of incredulity, to doubt of those things that are evident, so to determine of such things as the Spirit of God hath left (even in the judgment of the judicious) questionable, can be no less than presumption. Therefore as St. Augustine saith, that variety of translations is profitable for the finding out of the sense of the Scriptures ; so diversity of signification and sense in the margin, where the text is not so clear, must needs do good--yea, is necessary, as we are persuaded. We know that Sixtus Quintus expressly forbiddeth that any variety of readings of their vulgar edition should be put in the margin --which though it be not altogether the same thing to that we have in hand, yet it looketh that way--, but we think he hath not all of his own side his favorers for this conceit. They that are wise had rather have their judgments at liberty in differences of readings, than to be captivated to one, when it may be the other. If they were sure that their high priest had all laws shut up in his breast, as Paul the Second bragged, and that he were as free from error by special privilege as the dictators of Rome were made by law inviolable, it were another matter; then his word were an oracle, his opinion a decision. But the eyes of the world are now open, God be thanked, and have been a great while. They find that he is subject to the same affections and infirmities that others be, that his skin is penetrable; and therefore so much as he proveth, not as much as he claimeth, they grant and embrace.
In other words, the marginal notes are not clarifications of the meaning, they are alternative meanings because there is some uncertainty (or was uncertainty in the minds of the KJV translators).
Thus, taking the case of Isaiah 34:7, the KJV translators were not saying that "rhinocerots" is another word for "unicornes," but that it is a viable alternative reading at this place. In point of fact (as I've demonstrated in another post), they were right to be uncertain here, and both the main text and the margin are in error.
With this understanding, one can see why the marginal notes were deemed valuable by the translators. I note that Archbishop Richard Bancroft passed away in 1610, without seeing the conclusion of the translation work that he had been instrumental in authorizing and overseeing to some extent. Thus, perhaps his passing afforded an additional opportunity for the King James translators to bypass his rule. I will note that this entirely my own speculation.
Frederick Henry Ambrose Scrivener did an impressive study of the marginal notes. Scrivener points out that practice was not new to the King James, have been practiced since at least the Tyndale New Testament of 1525.
Scrivener notes that the alternative Hebrew original word readings are not easy to distinguish from the alternative translation of the same Hebrew readings.
Scrivener provides extensive notes, particularly on the marginal notes in the Apocrypha material, where the translators seemed to feel more free or at least felt greater need.
In the New Testament, Scrivener suggests that many notable marginal readings are derived, in one way or another, from Beza. This makes sense, given the high estimation of Beza's work at the time.
What is absent from the margins of the King James are comments on the passage. Many other versions included some (usually pithy) remarks about the text. While the KJV includes chapter summaries, the margins are (as far as I can determine) free of such annotations as one might find in the Geneva Bible or even the Bishops' Bible.
Some Additional Comments
1. Paragraph/Pilcrow Marks in the 1611 KJV
The final pilcrow of the New Testament is reproduced at right. It occurs at Acts 20:36. It remains a mystery as to why the KJV does not include any subsequent pilcrows. The idea that the typesetters ran out of the pilcrow type seems beyond belief, since it was not necessary to typeset all the pages at the same time.
Examples of KJV question mark at right (at the end of Galatians 3:1, at the end of Galatians 3:2, in the middle and end of Galatians 3:3, and in the middle of Galatians 3:4. This example also illustrates a marginal alternative reading of "so great" instead of "so many" for Galatians 3:4.
- Scrivener's explanation and comments regarding the marginal notes can be found here (link to Scrivener's comments)
- Timothy Berg has an interesting article here (link to article).
- An Exposition with Practicall Observations; continued upon the fifteenth, sixteenth and seventeenth chapters of the Book of Job: being the summe of twenty three lectures, etc., Joseph Caryl (1650) (Example)
- A Discourse concerning the Authority, Stile and Perfection of the Books of the Old and New Testament. With a continued illustration of several difficult texts of Scripture, etc
- Volume 2, John Edwards (1694) (Example)
- A Discourse concerning the Authority, Stile and Perfection of the Books of the Old and New Testament. With a continued illustration of several difficult texts of Scripture, etc
- Volume 3, John Edwards (1695) (Example)
- A Discourse of Conscience (1697) A. Bosvile (example 1)(example 2)(example 3)(example 4)