(ἶρις)
The rainbow which the writer of the Revelation saw around the throne of God was ‘like an emerald to look upon’ (Revelation 4:3). Flinders Petrie (Hasting's Dictionary of the Bible (5 vols) iv. 620) argues from this passage that σμάραγδος was not an emerald but a rock-crystal, as only a colourless stone can show a rainbow of prismatic colours. But while the glory encircling the throne was like a rainbow in shape, it may well have been conceived, not as prismatic, but as having the soft green colour of an emerald. Any nimbus round another body, as the halo of the moon or a candle, was called an ἶρις (Arist. Meteor. III. iv. 9). What the prophet depicts is a startling contrast: the very throne from which proceed lightnings and thunders (Revelation 4:5) is yet arched with emerald. In other words, mercy tempers justice: ‘Deus in judiciis semper foederis sui meminit’ (Grotius, quoted by H. Alford, Greek Testament5, Cambridge, 1875, p. 596). Noah’s rainbow and its traditional (mythological) explanation (Genesis 9:12-17) were doubtless in the background of the Seer’s mind. When the dread storm, in which the lightnings were Jahweh’s arrows and the thunder His voice, was passing, His bow appeared in the clouds as a sign that His anger was appeased. ‘The brilliant spectacle of the upturned bow against the dark background of the retreating storm naturally appeals to man as a token of peace and good-will from the god who has placed it there’ (J. Skinner, International Critical Commentary , ‘Genesis,’ Edinburgh, 1910, p. 172). The Jewish Rabbis would have agreed with the English pcet who apostrophizes the rainbow:
‘I ask not proud Philosophy
To teach me what thou art’
(T. Campbell, To the Rainbow, 3 f.).
They discouraged (Ḥagiga, 16a) the study of a mysterious phenomenon which was to them a sacrament or covenant of Divine grace.
James Strahan.