He feedeth on ashes; i.e. on vanity—on what can give no support or sustenance (comp. Proverbs 15:14; Hosea 12:1). A deceived heart. Either self-deceived, or imposed upon by illusions from without; e.g.
the seeming power of the idols, as seen in the victories and conquests of their worshippers. He cannot deliver his soul. The deceived soul is bound in trammels, which it feels to be irksome, and from which it would fain be free.
But it cannot deliver itself. Deliverance must come from some external source; in other words, man needs a Deliverer. Is there not a lie in my right hand? An idol is "a lie." It professes to have power, strength, ability to help and save, whereas it has no power at all.
It cannot even save itself. Savages often beat their fetishes. Diagoras of Melos threw an image of Hercules into the fire on which he was cooking his dinner, and bade Hercules make himself of some use by boiling his turnips.
The powerlessness of idols even to help themselves is represented with much force in the Book of Baruch (6:12-15, 17-22, 27, 49, etc.).