I asked her about the four colours which the beast had on his head. And she answered, and said to me, “Again you are inquisitive in regard to such matters.” “Yea, Lady,” said I, “make known to me what they are.” “Listen,” said she: “the black is the world in which we dwell: but the fiery and bloody points out that the world must perish through blood and fire: but the golden part are you who have escaped from this world. For as gold is tested by fire, and thus becomes useful, so are you tested who dwell in it. Those, therefore, who continue stedfast, and are put through the fire, will be purified by means of it. For as gold casts away its dross, so also will ye cast away all sadness and straitness, and will be made pure so as to fit into the building of the tower. But the white part is the age that is to come, in which the elect of God will dwell, since those elected by God to eternal life will be spotless and pure. Wherefore cease not speaking these things into the ears of the saints. This then is the type of the great tribulation that is to come.
Pastor (Shepherd) of Hermas Book First: Visions