The book of Psalms begins with the Psalm of the two ways, is the first and most important Psalm and synthesis of ethics in the Old Testament. The teaching of the Psalm contains two parts:
1) The two roads:
Good and evil are mentalities, moods of choosing. We choose between the righteousness and the sin. The good is to act by ethical principles, the Golden rule. The path of the good is known as a righteous life. Evil is practice the sin.
Blessed is the one
who does not walk in step with the wicked
or stand in the way that sinners take
or sit in the company of mockers
but whose delight is in the Law of the Lord,
and who meditates on his law day and night.
2) The law of the harvest and the sowing: Two roads, two destinations. This is so because of the law of the sowing and reaping that is present in the last part of the psalm. The Law of the sowing and reaping is a cosmic and universal law of returns, that is to say of prizes and punishments, of learning, of balance. This Law punishes the error and rewards the hit in the mark. The Psalm reflects a strong resemblance with the 4 Beatitudes of the Gospel of Luke 6: 20-23 and the four curses in Luke 6: 24-26.
The beatitude is edifying, progressive and gives fruits of blessing, the righteous or just man is compared with the tree that well-planted bears its fruit:
That person is like a tree planted by streams of water,
wich shields its fruit in season
and whose leaf does not wither-
whatever they do prospers
The misfortune is unjust, retardant, involutive and erroneous: the wicked are compared with the straw that the wind carries. The unfortunate or sinner is tied to the vicissitudes of destiny (wind) and does not depend on his effort or virtue:
Not so the wicked!
They are like chaff
that the wind blows away.
Therefore the wicked will not stand in the judgment,
nor sinners in the assembly of the righteous.
For the Lord watches over the way of the righteous,
but the way of the wicked leads to destruction.