The connection of this chapter with the preceding is somewhat obscure. Probably we are to regard Job as led to see, even while he is justifying God's ways with sinners (Job 27:8-23), how many and how great are the difficulties in the way of forming a single consistent theory of the Divine action, which shall be applicable to all cases.
Hence he comes to the conclusion that God is incomprehensible by man and inscrutable; and that it is only given to man to know him sufficiently for his practical guidance. To impress this on his hearers is his main object (verses 12-28); and, to impress it the more, he introduces it by a sharp contrast.
Wonderful as is man's cleverness and ingenuity in respect of earthly things and physical phenomena (verses 1-11), with respect to heavenly things and the spiritual world—wherewith true wisdom is concerned—he knows next to nothing.
All that he knows is just enough to guide his conduct aright (verse 28).