I will give you the treasures of darkness and the riches hidden in secret places, so that you may know that I am the LORD, the God of Israel, who calls you by name.
Cyrus was a Mede, descended (as some say) from Astyages king of Media. The pagan writers are not agreed in their accounts of his origin. Some tell us that in his infancy he was an outcast, left exposed, and was saved from perishing by a herdsman's wife.
Commenting on Isaiah 45:1-4
And I will give thee treasures of darkness, and hidden riches of secret places,.... What had been laid up in private places, and had not seen the light for many years. The Jewish Rabbins say (f), that Nebuchadnezzar having amassed together all the riches of the world, when he drew near his end, considered with himself to whom he should leave it; and being unwilling...
treasures of darkness--that is, hidden in subterranean places; a common Oriental practice. Sorcerers pretended to be able to show where such treasures were to be found; in opposition to their pretensions, God says, He will really give hidden treasures to Cyrus (Jer 50:37; Jer 51:13).