The inimitable grace and tenderness of the story are dissipated in a summary, but the main facts are these. A man of Bethlehem, with his wife Naomi and two sons, is driven by stress of famine to Moab, where the sons marry women of the land. In course of time, father and sons die, and Naomi resolves to return home. Ruth, one of her daughters-in-law, accompanies her, in spite of Naomi's earnest entreaty that she should remain in her own land. In Bethlehem, Ruth receives peculiar kindness from Boaz, a wealthy landowner, who happens to be a kinsman of Naomi; and Naomi, with a woman's happy instinct, devises a plan for bringing Boaz to declare himself a champion and lover of Ruth. The plan is successful. A kinsman nearer than Boaz refuses to claim his rights by marrying her, and the way is left open for Boaz. He accordingly marries Ruth, who thus becomes the ancestress of the great King David.
Why was this story told? The question of its object is to some extent bound up with the question of date; and for several reasons, this appears to be late. (1) In the Greek, Latin and modern Bibles, Ruth is placed after Judges; in the Hebrew Bible it is placed towards the end, among the Writings, i.e. the last division, in which, speaking generally, only late books appear. Had the book been pre-exilic, it is natural to suppose that it would have been placed after Judges in the second division. Some indeed maintain that this is its original position; but it is easier to account for its transference from the third division to the second, as a foil to the war-like episodes of the judges, than for its transference from the second to the third. (2) The argument from language is perhaps not absolutely decisive, but, on the whole, it is scarcely compatible with an early date. Some words are pure Aramaic, and some of the Hebrew usages do not appear in early literature, e.g., "fall," in the sense of "fall out, issue, happen," iii.18. (3) The opening words -- "In the days when the judges judged," i.1 -- suggest not only that those days are past, but that they are regarded as a definite period falling within an historical scheme. The book must be, at any rate, as late as David -- for it describes Ruth as his ancestress, iv. l7 -- and probably much later, as the implication is that it is a great thing to be the ancestress of David. The reverence of a later age for the great king shines through the simple genealogical notice with which the story concludes. (4) Further, the old custom of throwing away the shoe as a symbol of the abandonment of one's claim to property, a custom familiar in the seventh century B.C. (Deut. xxv.9f.) is in iv.7 regarded as obsolete, belonging to the "former time." The cumulative effect of these indications is strongly to suggest a post-exilic date. Not perhaps, however, a very late one: a book as late as the Maccabean period would hardly have reflected so kindly a feeling towards the foreigner (cf. Esther).
The story probably rests upon a basis of fact. David's conduct in putting his parents under the protection of the king of Moab (I Sam. xxii.3, 4) would find its simplest explanation, if he had been connected in some way with Moab, as the book of Ruth represents him to have been; whereas a later age would hardly have dared to invent a Moabite ancestress for him, had there been no tradition to that effect.
The object of the book has been supposed by some to be to commend the so-called levirate marriage. This is improbable: not so much because the marriage was not strictly levirate, since neither Boaz nor the kinsman was the brother-in-law of Ruth -- it would be fair enough to regard this as a legitimate extension of the principle of levirate marriage, whose object was to perpetuate the dead man's name -- but rather because this is a comparatively subordinate element in the story.
The true explanation is no doubt to be sought in the fact that Ruth the Moabitess is counted worthy to be an ancestress of David; and, if the book be post-exilic, its religious significance is at once apparent. It was in all probability the dignified answer of a man of prophetic instincts to the rigorous measures of Ezra, which demanded the divorce of all foreign women (Ezra ix. x, cf. Neh. xiii.23ff.); for it can hardly be doubted that there is a delicate polemic in the repeated designation of Ruth as the Moabitess, i.22, ii.2, 6, 21, iv.5, 10 -- she even calls herself the "stranger," ii.10. It would be pleasant to think that the writer had himself married one of these foreign women. In any case, he champions their cause not only with generosity but with insight; for he knows that some of them have faith enough to adopt Israel's God as their God, i.16, and that even a Moabitess may be an Israelite indeed. Ezra's severe legislation was inspired by the worthy desire to preserve Israel's religion from the peril of contagion: the author of Ruth gently teaches that the foreign woman is not an inevitable peril, she may be loyal to Israel and faithful to Israel's God. The writer dares to represent the Moabitess as eating with the Jews, ii. l4 -- winning by her ability, resource and affection, the regard of all, and counted by God worthy to be the mother of Israel's greatest king. The generous type of religion represented by the book of Ruth is a much needed and very attractive complement to the stern legalism of Ezra.