The thought is that Job must exercise faith in a situation in which he can sense nothing. Don’t give up – God knows how he will bless you already.
But how beautiful a thing is justice and how wonderful that God is so committed to it. Justice will find a way through the most complex of cases and allocate to each one what is right, perfectly vindicating the judge and honouring the law by which he proceeds. But in the case of God’s children there is something even more wonderful than justice for grace is mixed with it, and we receive much more good from the Lord than plain justice would dispense.
An alternative translation (RSV, NIV, ESV) treats the verse as an argument from the lesser to the greater: if God does not hear a vain petition (verse 13), how much less will he hear you ‘when you say you do not see him, that the case is before him, and that you are waiting for him’; that is, how much less does he regard your cry when by your own admission you say that you do not detect his presence. This thought is alien to the Bible which exhorts faith even when we see nothing and certainly does not make God’s answer to our prayer conditional on our perceiving him.