Aker an ancient earth-god, who also presided over the western and eastern borders of the Underworld, signifying the horizon. In early representations, Aker is shown as a narrow strip of land with a human or lion head at both ends. But also later he was shown as the foreparts of two opposing lions, sometimes with human heads, facing away from each other. Mostly Aker was depicted as two lions seated back to back, facing away from each other. In the later period they made up the Akeru and were called "Yesterday" (Egyptian Sef) and "Tomorrow/Today" (Egyptian Tuau), as one faces to the east where the sun rises and the other to the west where the sun sets and descends into the Underworld. In between them is the sign of the horizon. Thus the area between the lion's backs often shows the circle of the sun as if rising between two hills. Aker also guards the gate to the Underworld and opens it for the King to pass through. He was also known to absorb the poison from the body of anyone bitten by a snake and he neutralizes the venom in the belly of a person who has swallowed an obnoxious fly.
More importantly, he imprisons the coils of the snake, Apophis, after it is hacked to pieces by Isis, and Aker could, along his back, provide a secure passage for the sun-god's boat as it traveled from west to east during the hours of the night.
Aker was not worshipped as a Netjer, and was more connected to the primeval concepts and earth powers.
The hieroglyph for a lion is .
The hieroglyphic origin of Libra is seen as the sun rising between the mountains. This is known as Akhet representing the horizon (i.e. sunrise/sunset) which the sun emerged and disappeared. It is similar to the two peaks of the Djew or mountain symbol (i.e. western peak is Manu, the eastern peak is Bakhu) with the solar disk in the center. This was guarded by Aker, a double lion god, seen as a sphinx with the body of a lion (i.e. Great Sphinx of Giza) which may be seen on ESNE Plate 79, and getting the name Harmakhet, "Horus in the Horizon."
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Libra Sign.