To proclaim the acceptable year of the Lord. An "acceptable year," or "year of acceptance," is a space of time during which God would be pleased to accept such as repented and turned to him. It is, of course, not intended to limit the space to a "year."
The space is rather the term of our sojourn here below. The day of vengeance. The "day" of vengeance is contrasted with the "year" of acceptance, to indicate God's long-suffering and patience towards sinners (comp.
Isaiah 34:8; and see also Exodus 20:5, Exodus 20:6). To comfort all that mourn; i.e. all who "sorrow after a godly sort" (2 Corinthians 7:11)—all who mourn their transgressions and shortcomings, their "sins, negligences, and ignorances," with a hearty desire to be rid of them, and to serve God truly in the future.