The master thought of this psalm is the law of Jehovah. The obedient and disobedient are placed in sharp contrast. This contrast is vividly seen by bringing together the first and last words of the psalm-"blessed," "perish." The former word describes the issue of obedience; the latter, the result of disobedience. The conditions of blessedness are stated negatively and positively. Negatively, there must be complete separation from fellowship with those who are disobedient. The graduation in description must not be omitted; "walketh," "standeth," "sitteth"; "counsel," "way," "seat"; "wicked," "sinners," ''scornful." The positive condition is twofold delight and meditation in the Law. Moreover, this must be continuous, "day and night."
The experience of the blessed is described under the figure of a tree bearing fruit, with evergreen leaf. Moreover such a man prospers in all he does. Then comes the contrast. Let the statement, "The wicked are not so," be considered in the light of all that has been said, that is, in the former part of the psalm cancel the negations where they stand and insert them where they are not. The condition of the wicked is then summarized and the contrast is perfected. Instead of the tree planted, they are chaff driven away. They will be unable to stand the test of judgment, and therefore are excluded from the assembly of the righteous.
The psalm ends with a summary. "The way of the righteous" is known to Jehovah. "The way of the wicked" perishes, that is, runs out, and is lost in the desert.