The word "prevent" is now generally used to represent the idea of hindrance. Here it means to 'allow' or to open the floodgates of blessing.
It also means that the Lord "goes before" us with the blessings of his goodness as a pioneer marking the path ahead of us and making it safe.
He goes ahead of us to make crooked ways straight, and rough places smooth; or, as one who strews flowers in the path of another, to make the way beautiful and pleasant to walk.
A large portion of our blessing is given to us before our asking or seeking:
Existence, reason, intellect, the knowledge of Christ, and Christ Himself, with many other things are unsought blessings and yet bestowed on mankind.
No one ever asked for a Savior until God of His own motion promised "the seed of the woman" that would be our Redeemer.
Our acceptance of this Savior, Jesus Christ, sets the stage for us to be crowned with the blessing of salvation both now, and forever in Eternity!