18. "The peaceable fruit of righteousness." He says "righteousness"; because it is itself the true wisdom. As in the case of the earthly wisdom, after the characteristic description came its results; so in this verse, in the case of the heavenly wisdom. There the results were present; here, future.
      fruit . . . sown--Compare Ps 97:11; Isa 61:3, "trees of righteousness." Anticipatory, that is, the seed whose "fruit," namely, "righteousness," shall be ultimately reaped, is now "sown in peace." "Righteousness," now in germ, when fully developed as "fruit" shall be itself the everlasting reward of the righteous. As "sowing in peace" (compare "sown in dishonor," 1Co 15:43) produces the "fruit of righteousness," so conversely "the work" and "effect of righteousness" is "peace."
      of them that make peace--"by (implying also that it is for them, and to their good) them that work peace." They, and they alone, are "blessed." "Peacemakers," not merely they who reconcile others, but who work peace. "Cultivate peace" [ESTIUS]. Those truly wise towards God, while peaceable and tolerant towards their neighbors, yet make it their chief concern to sow righteousness, not cloaking men's sins, but reproving them with such peaceable moderation as to be the physicians, rather than the executioners, of sinners [CALVIN].

JFB.