the dead know not any thing. See and Compare Ecclesiastes 9:10; Psalms 6:5; Psalms 30:9; Psalms 31:17; Psalms 88:11.Isaiah 38:18; Isaiah 38:19.
a reward. any advantage [to them].
memory. the faculty of remembering. See note on "them", below.
them. The Hebrew suffix "them" must be taken as the subject in all the four nouns alike. As in Ecclesiastes 9:6, the possessive pronoun "their" is, and must be, taken alike in each case.
is forgotten. ceases to exist, as in Psalms 77:9, where it is parallel with "clean gone for ever "and "evermore", and in the next verse here(Ecclesiastes 9:6), where it stands parallel with "perished" and "for ever".