Isis and Osiris (labeled)
Statues of Isis, holding the ankh, and her brother-husband Osiris (who typically has green skin), with whom she conceives, via black rite resurrection sex, the savior god Horus.
In Egyptian mythology, Isis (CR:22) is an Egyptian mother goddess; wife-sister of Osiris, sister of Nephthys, mother of Horus, noted for having played a key role in the resurrection of the dead Osiris, after his hacking into 14 pieces (see: Orion) by the god Set, as told in the famous "Passion of Osiris". [1]

Sirius
In astro-theology, the star Sirius, aka the brightest star in the sky, was originally personified by the goddess Sopdet; this goddess, in turn, was later syncretized with Isis, to the effect that Isis was associated with Sirius. [2]

Synonyms | Morphs

The general Isis goddess model, according to Wallis Budge (1904), morphed outside of Egypt as follows: [8]

“From the works of classical writers we know that her worship spread from Egypt into several places in Western Europe, and she was identified with Persephone, Tethys, Athene, etc., just as Osiris was identified with Hades or Pluto, Dionysus-Bacchus, and other foreign gods.”

In 43BC, according to Budge, temples were built in honor of Isis and Serapis (Ѻ), i.e. Osiris-Apis, the Greco-Roman Osiris god syncretism, created per order of Ptolemy I.

Nile River | Annual flood
On Jun 25, in Egypt, annually, what is called the helical rising of Sirius occurs when the star and sun are sufficiently separated so that—for the first time in 70 days—Sirius can be seen on the horizon just before dawn. The day when Sirius is first sighted marks the start of the annual Nile River flood.

“The Egyptians hold the festival of Isis at the time when they say she is mourning for Osiris. At that time the Nile begins to rise, and it is a common saying among the natives that it is the tears of Isis that cause the river to rise and water the fields.”
Apuleius (c.165AD), Eleventh Book; cited by Wallis Budge (1904) [8]

It was believed, as summarized above, that the annual flooding of the Nile River was caused by Isis weeping for her husband. [7]

Mary
It has been known for some time that Isis is the main goddess character behind the Christian character of the Virgin Mary; some quotes of which are as follows:

“The Virgin Mary seems to have done wonders in this way; so that what Juvenal said of the goddess Isis may be applied to her, that the Painters get their livelihood out of her.”
— John Poynder (1818), Popery of the Religion of Heathenism (pg. 19)

“Among the Egyptians, the zodiacal Isis is a virgin mother.”
Romualdo Gentilucci (1848), Life of the Most Blessed Virgin Mary [6]

“In Osiris the Christian Egyptians found the prototype of Christ, and in the pictures and statues of Isis suckling her son Horus, they perceived the prototype of the Virgin Mary and her Child.”
Wallis Budge (1899), Egyptian Ideas of the Future Life [4]

Isis, alone of all the pagan goddesses, was the ‘great forerunner’ of the Virgin Mary.”
— Reginald Witt (1971), Isis and the Greco-Roman World [5]

“There is much argument that the Isis cult influenced the portrayal of the Christian Virgin Mary, who was also known as Stella Maris and whose portraits with the Christ often bear a striking similarity to those of Isis with Horus.”
Michael Jordan (1993), Encyclopedia of Gods

“Although there are arguments among scholars that Mary’s imagery is closer to that of Kybele, who became the Roman Magna Mater, it is the Egyptian goddess Isis who provided much of the inspiration. The Greeks and Romans, thoroughly besotted in their adoration of most things Egyptian, had identified Isis as the Star of the Sea and they believed her to make her nightly appearance in the heavens as the north star. Stella Maris is a title loaded with meaning since the sea has always been regarded as a source of bounty and fertility. So it does not come wholly as a surprise to discover that, from about the time of the ninth century, Mary was also enjoying the title of Stella Maris.”
Michael Jordan (2001), The Historical Mary [3]
Isis (and Horus) and Mary (and Jesus)
A comparison, by Dorothy Murdock, of Isis suckling Horus to Mary suckling Jesus. (Ѻ)

“It is impossible to ignore the similarities between the Egyptian quarternity: Isis and Nephthys (known as 'the Two Goddesses' in Egypt), Osiris and Set (personifications of life and death), and the leading characters of the Eleusinian drama: Demeter and Persephone (also known simply as 'the Two Goddesses'), Dionysus and Hades. Diodorus of Sicily, first century BC, clearly states that the initiatory rites of Demeter in Eleusis were transferred from Egypt (Diodorus Siculus, 1.29.2). Later he states: The rite of Osiris is the same as that of Dionysus and that of Isis very similar to that of Demeter; the names alone having been interchanged, and the punishments in Hades of the unrighteous, the Fields of the Righteous and the fantastic conceptions, current among the many - all these were introduced by Orpheus in imitation of the Egyptian funeral customs.' (1.96.4-5).”
Timothy Freke and Peter Gandy (2001), Jesus and the Lost Goddess [9]

(add discussion)

References
1. Jordan, Michael. (1993). Encyclopedia of Gods: Over 2,500 Deities of the World. Facts on File, Inc.
2. Oakes, Lorna and Gahlin, Lucia. (2002). Ancient Egypt: an Illustrated Reference to the Myths, Religions, Pyramids and Temples of the Land of the Pharaohs (Sah, pgs. 331, 425; Sopdet, 331, 399). Hermes House.
3. Jordan, Michael. (2001). The Historical Mary: Revealing the Pagan Identity of the Virgin Mother (pg. 275). Seastone.
4. Budge. Wallis. (1899). Egyptian Religion: Egyptian Ideas of a Future Life (pg. 81) (Ѻ). Publisher.
5. (a) Witt, Reginald E. (1971). Isis and the Greco-Roman World (Isis in the Ancient World) (§:Great Forerunner, pgs. 269-81). JHU Press, 1997.
(b) Carroll, Michael P. (1992). The Cult of the Virgin Mary: Psychological Origins (pg. 111). Princeton University Press.
6. Gentilucci, Romualdo. (1848). Life of the Most Blessed Virgin Mary (pgs. 25-26). E. Dunigan, 1860.
7. Bob. (2015). “Temple of Isis on Philae Island Aswan” (Ѻ), Blogspot, Jun.
8. Budge, Wallis. (1904). The Gods of the Egyptians, Volume Two (pgs. 216-17; Isis weeping, pg. 219). Dover, 1969.
9. Freke, Timothy and Grandy, Peter. (2001). Jesus and the Lost Goddess: The Secret Teachings of the Original Christians (Osiris, 18+ pgs; quote, pg. 255). Random House.

External links
Isis – Wikipedia.

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