Isaiah 38:7

This shall be a sign unto thee... — The offer reminds us of that made to Ahaz; but it was received in a far different spirit. In 2 Kings 20:8 the story is more fully told. Hezekiah asks for a sign, and is offered his choice. Shall the shadow go forward or backward? With something of a child-like simplicity he chooses the latter, as the more difficult of the two. The sun-dial of Ahaz, probably, like his altar (2 Kings 16:10), copied from Syrian or Assyrian art [the mention of a sun-clock is ascribed by Herodotus (ii. 109) to the Chaldæans], would seem to have been of the form of an obelisk standing on steps (the literal meaning of the Hebrew word for dial), and casting its shadow so as to indicate the time, each step representing an hour or half-hour. The nature of the phenomenon seems as curiously limited as that of the darkness of the crucifixion. There was no prolongation of the day in the rest of Palestine or Jerusalem, for the backward movement was limited to the step-dial. At Babylon no such phenomenon had been observed, and one ostensible purpose of Merôdach-baladan’s embassy was to investigate its nature (2 Chronicles 32:31). An inquiry into the causation of a miracle is almost a contradiction in terms, but the most probable explanation of the fact recorded is that it was the effect of a supernatural, but exceedingly circumscribed, refraction. A prolonged after glow following on the sunset; and reviving for a time the brightness of the day, might produce an effect such as is described to one who gazed upon the step-dial.