We know that God blesses us. But the Bible also speaks of us blessing God. How does that work? How can mere human beings “bless the LORD”? What can we do to benefit Him, the One who needs nothing?
I learned in Bible class recently that there is a blessing from greater to lesser, when God gives gifts to mortals, but also when kings bestow gifts to their subjects, etc. But there is also a blessing from lesser to greater. This kind of blessing–when the subject blesses the king or the mortal blesses God–consists mainly of thanksgiving.Thus, when we bless our food, we are thanking God for it.
It is also possible to bless someone in the name of the “greater,” as when pastors, in the name of God–that is, in His stead and on His behalf–pronounce a blessing on the congregation as they convey His gifts.
Check out this from C. H. Spurgeon, who discusses this issue at length. He stresses gratitude, but also goes into some other sense of the term.