If the book of Judges (especially in the latter part of the book) presents people doing what is right in their own eyes, being self-absorbed and self-driven, then the book of Ruth presents the very opposite, where Boaz and Ruth in particular are driven by concerns for others, by the issues of hesed. This is perhaps most vivid in the contrast between Samson (dominated by self-absorption) and Boaz (driven by his concern for the welfare of the two widows).
