Ennead (Greek Ἐννεάς, meaning the nine), an ancient Greek translation of the Egyptian word, Pesedjet, consists of a grouping of nine deities, most often appearing in the context of Egyptian mythology.
As a multiple, three times three, the number nine became associated, religiously, as a great cardinal power, and many ancient peoples considered groupings of nine deities very important. It is likely that this belief was imposed upon the diverse groupings of deities who were included in the Egyptian pantheon and which differed from place to place.
The ancient Egyptians established multiple Pesedjets. The Pyramid Texts, originating in the fifth and sixth dynasty of the Old Kingdom, mention the Great Pesedjet, the Lesser Pesedjet, the Dual Pesedjet, plural Pesedjets, and even the Seven Pesedjets. Some pharaohs established pesedjets that incorporated themselves among the deities; most notably, Seti I in his temple at Redesiyah worshipped a pesedjet that combined six important deities with three deified forms of himself.
Interestingly, the original Egyptian term, Pesedjet, usually translated as Ennead in Greek, does not necessarily mean a group of nine. Some pesedjets had a varying number of deities throughout the three thousand years of known Egyptian history and may have contained as few as seven or, as many as ten deities. The Greeks occupied Egypt for almost three hundred years (before being overcome by the Roman Empire) and the Greek rulers and administrators in Egypt adopted the Egyptian culture and religion in an attempt to avoid the impression of a foreign occupation.
Citizens of Greece travelled to Egypt and explored it in great detail. They became most familiar with the current mythology and religious practices as presented to them by religious leaders whose retention of political power was tied to the interweaving of religion and state affairs in Egypt. Thousands of years of changing beliefs and important secrets often, were omitted or not revealed to foreigners, even ones who had occupied the country for a few hundred years.
Much was written about Egypt and what was understood about its culture by Greek historians, geographers, and philosophers. Their writings greatly influenced ideas about the Egyptian culture among the educated of the time in a language that was known broadly. The Greeks did, however, attempt to establish parallels between the ancient Egyptian culture and their own, drawing comparisons to their own culture and religious concepts, apparently seeking an identification with the long history of Egypt and asserting that Egyptian deities were derived from those of the Greeks. This created a "filter" that distorted many concepts in their writings.
When the Romans succeeded the Greeks in the occupation of Egypt, no religion was established officially. Egyptian temples continued to be used, some Roman names were applied to deities that the Greeks had redefined, and some emperors sought to be included among the deities, but other religions were practiced in them as well and new religious sects were forming. Some Egyptian cults were carried, relatively intact, throughout the vast Roman Empire, for instance, temples to Isis were built in Rome and as far away as Britain.
Greek remained the language of the highly-educated, especially in the Eastern Roman Empire. Hence, Greek often is found as the language used to describe Egyptian names, locations, and religious concepts and that tradition often has continued although the Egyptian names and words have been known since the breakthrough to understanding their unfamiliar language, written in two forms, via the Rosetta Stone. Following the collapse of the Roman Empire, Arabic writings became the repository of knowledge for several centuries and it also became the language of place names in Egypt. Once a means of deciphering the original Egyptian hieroglyphic, its related hieratic, and Demotic writing became available in 1822. Better understanding of the remains of the ancient culture followed in 1858, when its translation was published, but so much scholarly work in diverse languages and the existence of many different names for deities, people, places, and topics continues to create confusion, hence the use of a Greek name is herewith used for an Egyptian custom that doesn't quite fit the meaning for the pantheons so named.
The most important of the Egyptian pesedjets, the so-called Great Ennead (also called the Heliopolis Ennead), consisted of Ra, his children Shu and Tefnut, and their descendants Geb, Isis, Nephthys, Nut, Osiris, and Set. It was defined in the Egyptian city of Annu (place of pillars), the Egyptian name for what the Greeks called Heliopolis (sun city), in the last dynasty of the Old Kingdom and other deities who had existed for a thousand years were ignored in order to stress the importance of this local sun deity. The location of the ancient city was five miles east of the Nile River, north of the Delta. The city was later called in Arabic ˁAyn Šams (the eye of the sun). Late in the Ptolemy Dynasty, the Greek rulers failed to favor this local sun deity and their center of learning shifted to the newly-built city of Alexandria, by the first century BC, Strabo found the once great centers at Annu deserted, and the town itself almost uninhabited, although priests remained.
The origins of this grouping now remain uncertain. In some versions Ra mated with Iusaaset, the great one who comes forth, and their children were Shu and Tefnut. Consequently, Iusaaset was seen as the mother and grandmother of the deities. Sometimes she is described as a "shadow" in this pesedjet.
Up until the mid-twentieth century theories of Egyptologists postulated that the Heliopolis priesthood established this pesedjet in order to place their local sun-god, Ra, above all other deities such as Osiris, however, many later Egyptologists now question this. It appears almost certain, however, that the Great Ennead first appeared during the decline of Ra's cult in the sixth dynasty and, that after introduction of the new pesedjet, the cult of Ra soon saw a great resurgence until the worship of Horus gained prominence. Afterward worship focused on the syncretistic solar deity Ra-harakhty (Ra, who is Horus of the Two Horizons). During the Amarna Period, Akhenaten introduced worship of aother solar deity, Aten, the deified solar disc. He built a temple in Annu, named Wetjes Aten (wṯs ỉtn, Elevating the Sun-disc). Blocks from this temple later were used to build walls to the medieval city of Cairo and are included in some of the city gates. The cult of the Mnevis bull, an embodiment of Ra, had its centre here and established a formal burial ground for the sacrificed bulls north of the city.
From the primeval waters represented by Nun, a mound appeared. Upon the mound sat Ra, who had begotten himself. Bored and alone, he masturbated or, according to other stories, spat, producing air, Shu, and moisture, Tefnut. Shu and Tefnut in turn mated and she gave birth to the earth, Geb, and the sky, Nut. Because of their initial closeness, Geb and Nut engaged in continuous copulation until Shu separated them, lifting Nut into her place in the sky. The children of Geb and Nut were Isis, Nephthys, Osiris, and Seth.