If any of you lack wisdom - Wisdom signifies in general knowledge of the best end, and the best means of attaining it; but in Scripture it signifies the same as true religion, the thorough practical knowledge of God, of one's self, and of a Savior.
Let him ask of God - Because God is the only teacher of this wisdom.
That giveth to all men liberally - Who has all good, and gives all necessary good to every one that asks fervently. He who does not ask thus does not feel his need of Divine teaching. The ancient Greek maxim appears at first view strange, but it is literally true: -
Αρχη γνωσεως της αγνοιας ἡ γνωσις .
"The knowledge of ignorance is the beginning of knowledge."
In knowledge we may distinguish these four things: -