In Mackey’s Revised History of Freemasonry, by Robert Ingham Clegg, et. al., we find the following: [Volume VII, pp. 2135 – 2137]
“Figures 3, 5, and 6 are different forms of Nergal. The word Ner-Gal divides into two parts: Ner signifies light, or luminary, etc., and gal signifies to roll, revolve, a revolution, a circuit, the two together implies the revolving or returning light. If this be truly descriptive of Nergal, there is nothing improbable in considering the rooster as allusive to it, since the vigilance of the rooster is well known, and that he gives due notice of the very earliest reappearance of light, morning after morning. There are different senses in which light may be taken, besides its reference to natural light:
1. Deliverance from any singular danger, or distress. Esther 8:6.
2. Posterity; a son, or successor. 1 Kings 11:36; 2 Chron. 21:7.
3. Resurrection or something very like it. Job 33:28, 30; Psalm 97:11.
In the figures 3, 5, and 6 there is no allusion to the first of these principles, but they have a strong reference to the second, Posterity, and the idea of fecundity or fertility is expressed in the adaptation of the figure of a rooster, which signifies the returning of light.
In Figure 5, which is taken from a gem in the Gallery of Florence, Italy, two roosters are yoked to the car of Cupid, and driven by one Cupid and led by another; and not merely as if harnessed to a common car, but as if they had been in a race and had come off victorious; as the driving Cupid carries a palm-branch, which is the reward of victory, obtained by these his emblematical figures.
In Figure 3 we have a car with a rooster standing in the attitude of crowing and flapping his wings; which is the custom of this bird on certain occasions. The star shown is the star of Venus, and distinguishes this equipage as the consecrated vehicle of that supreme goddess of love and beauty.  At a short distance in the background sits Hymen, the god of marriage and conjugality; his torch brightly blazing; at his feet is a rooster crowing, etc., in a manner and attitude very like the other; and with precisely the same allusions. The indication of this allegory is the influence of Venus and Hymen, the genial powers of vitality, on the renovation of life, in human posterity.
As the extinction of lamps, or torches, indicated utter desolation, loss of children and misery, so on the contrary we are led by the brightly blazing torch to imply the joy of connubial or marriage engagements.
The Figure 6 represents a rooster holding in his bill two ears of corn; he is attended by Mercury, having a Caduceus or wand in one hand, and a bag of money in the other. This gem has puzzled the learned. Montfaucon says, ‘To see Mercury with a rooster is common enough; but to see him walking before a rooster larger than himself, is what I have never noticed, except in this representation. It may denote that the greatest qualities of Mercury is vigilance. The rooster holding the corn in his bill, may, perhaps, mean that vigilance only can produce plenty of the productions necessary to the support of life.’ Ancient mythology adopted various representations of the human form.