BASILIDES, one of the most conspicuous exponents of Gnosticism, was living at Alexandria probably as early as the first decades of the 2nd century. It is true that Eusebius, in his Chronicle, dates his first appearance from A.D. 133, but according to Eusebius, Hist. Eccl. iv. 7 §§ 6-8, Agrippa Castor, who lived under Hadrian (117-138), already wrote a polemic against him, so that his activity may perhaps be set back to a date earlier than 138. Basilides wrote an exegetical work in twenty-four books on "his" gospel, but which this was is not known. In addition to this there are certain writings by his son Isidorus "Peri prosphuous psuchês"; "Exêgêtika" on the prophet Parchor ; "Ethika". The surviving fragments of these works are collected and commented on in Hilgenfeld's Ketzergeschichte, 207-218. The most important fragment published by Hilgenfeld (p. 207), part of the 13th book of the Exegetica, in the Acta Archelai et Manetis c. 55, only became known in its complete form later, and was published by L. Traube in the Sitzungsbericht der Münchener Akad., phil. histor. Kl. (1903), pp. 533-549. Irenaeus (Adv. Haer. i. 24 §§ 3-7) gives a sketch of Basilides' school of thought, perhaps derived from Justin's Syntagma. Closely related to this is the account in the Syntagma of Hippolytus, which is preserved in Epiphanius, Haer. 24, Philaster, Haer. 32, and Pseudo-Tertullian, Haer. 4. These are completed and confirmed by a number of scattered notices in the Stromateis of Clemens Alexandrinus. An essentially different account, with a pronounced monistic tendency, is presented by the so-called Philosophumena of Hippolytus (vii. 20-27; x. 14). Whether this last account, or that given by Irenaeus and in the Syntagma of Hippolytus, represents the original system of Basilides, has been the subject of a long controversy. (See Hilgenfeld p. 205, note 337.) The most recent opinion tends to decide against the Philosophumena; for, in its composition, Hippolytus appears to have used as his principal source the compendium of a Gnostic author who has introduced into most of the systems treated by him, in addition to the employment of older sources, his own opinions or those of his sect. The Philosophumena, therefore, cannot be taken into account in describing the teaching of Basilides (see also H. Stachelin, "Die gnostischen Quellen Hippolyts" in Texte und Untersuchungen, vi. 3; and the article Gnosticism). A comparison of the surviving fragments of Basilides, moreover, with the outline of his system in Irenaeus-Hippolytus (Syntagma) shows that the account given by the Fathers of the Church is also in the highest degree untrustworthy. The principal and most characteristic points are not noticed by them. If we assume, as we must needs do, that the opinions which Basilides promulgates as the teaching of the "barbari" (Acta Archelai c. 55) were in fact his own, the fragments prove him to have been a decided dualist, and his teaching an interesting further development of oriental (Iranian) dualism. Entirely consistent with this is the information given by the Acta Archelai that Basilides, before he came to Alexandria, had appeared publicly among the Persians (fuit praedicator apud Persas); and the allusion to his having appealed to prophets with oriental names, Barkabbas and Barkoph (Agrippa in Eusebius Hist. Eccl. iv. 7 § 7). So too his son Isidorus explained the prophecies of a certain Parchor ( = Barkoph) and appealed to the prophecies of Cham  (Clemens Alexandrinus, Stromat. vi. 6 § 53). Thus Basilides assumed the existence of two principles, not derivable from each other: Light and Darkness. These had existed for a long time side by side, without knowing anything of each other, but when they perceived each other, the Light had only looked and then turned away; but the Darkness, seized with desire for the Light, had made itself master, not indeed of the Light itself, but only of its reflection (species, color). Thus they had been in a position to form this world: unde nec perfectum bonum est in hoc mundo, et quod est, valde est exiguum. This speculation is clearly a development of that which the Iranian cosmology has to tell about the battles between Ahura-Mazda and Angro-Mainyu (Ormuzd and Ahriman). The Iranian optimism has been replaced here by a strong pessimism. This material world is no longer, as in Zoroastrianism, essentially a creation of the good God, but the powers of evil have created it with the aid of some stolen portions of light. This is practically the transference of Iranian dualism to the more Greek antithesis of soul and body, spirit and matter (cf. Irenaeus i. 24 § 5: animae autem eorum solam esse salutem, corpus enim natura corruptibile existit). The fundamental dualism of Basilides is confirmed also by one or two other passages. In the parable of the rich man and Lazarus, Basilides saw the proof of naturam sine radice et sine loco rebus supervenientem (Acta Archelai). According to Clemens, Strom. iv. 12 § 83, etc., Basilides taught that even those who have not sinned in act, even Jesus himself, possess a sinful nature. It is possibly also in connexion with the dualism of his fundamental views that he taught the transmigration of souls (Origen in Ep. ad Rom. lib. v.; Opp. de la Rue iv. 549; cf. Clemens, Excerpta ex Theodoto, § 28). Isidorus set up celibacy, though in a modified form, as the ideal of the perfect (Clemens, Strom. iii. 1 § 1, etc.) Clemens accuses Basilides of a deification of the Devil ("theiazein ton diabolon"), and regards as his two dogmas that of the Devil and that of the transmigration of souls (Strom. iv. 12 § 85: cf. v. 11 § 75). It is remarkable too that Isidorus held the existence of two souls in man, a good and a bad (Clemens, Strom. ii. 20 113); with which may be compared the teaching of Mani about the two souls, which it is impossible to follow F, Ch. Baur in excluding,  and also the teaching of the Pistis Sophia (translated by C. Schmidt, p. 182, etc.). According to Clemens (Strom. ii. 20 § 112), the followers of Basilides spoke of "pneumata tina prosêrtêmena têi logikêi phuchêi kata tina tarachon kai sunchusin archikên": that is to say, here also is assumed an original confusion and intermingling. Epiphanius too tells us that the teaching of Basilides had its beginning in the question as to the origin of evil (Haer. xxiv. 6).
Now, of this sharply-defined dualism there is scarcely a trace in the system described by the Fathers of the Church. It is therefore only with caution that we can use them to supplement our knowledge of the true Basilides. The doctrine described by them that from the supreme God (the innatus pater) had emanated 365 heavens with their spirits, answers originally to the astronomical conception of the heavens with their 365 daily aspects (Irenaeus i. 24. 7; Trecentorum autem sexaginta quinque caelorum locales positiones distribuunt similiter ut mathematici). When, therefore, the supreme God is called by the name "Abrasax" or "Abraxas", which contains the numerical value 365, it is worthy of remark that the name of the Persian god Mithras ("Meithras") also was known in antiquity to contain this numerical value (Jerome in Amos 3; Opp. Vallarsi VI. i. 257). Speculations about the Perso-Hellenistic Mithras appear to have been transferred to the Gnostic Abraxas. Further, if the Pater innatus be surrounded by a series of (from five to seven) Hypostases (according to Irenaeus i. 24. 3; "Nous, Logos, Phronêsis, Sophia, Dunamis"; according to Clemens, Strom. iv. 25 § 164, "Dikaiosunê" and "Eirênê" may perhaps be added), we are reminded of the Ameshas-spentas which surround Ahura-Mazda. Finally, in the system of Basilides, the (seven ?) powers from whom this world originates are accepted as the lowest emanations of the supreme God. This conception which is repeated in nearly every Gnostic system, of (seven) world-creating angels, is a specifically oriental speculation. The seven powers which create and rule the world are without doubt the seven planetary deities of the later Babylonian religion. If, in the Gnostic systems, these become daemonic or semi-daemonic forces, this points to the fact that a stronger monotheistic religion (the Iranian) had gained the upper hand over the Babylonian, and had degraded its gods to daemons. The syncretism of the Babylonian and the Persian religion was also the nursing-ground of Gnosticism. When, then, Basilides identified the highest angel of the seven, the creator of the worlds, with the God of the Jews, this is a development of the idea which did not occur until late, possibly first in the specifically Christian circles of the Gnostics. We may note in this connexion that the system of Basilides ascribes the many battles and quarrels in the world to the privileged position given to his people by the God of the Jews. 
It is at this point that the idea of salvation is introduced into the system. The confusion in the world has meanwhile risen to such a pitch that the supreme God sends his Nous, who is also called Christ, into the world (Irenaeus i. 24. 4). According to Clemens, the Saviour is termed "pneuma diakonoumenon" (Strom. ii. 8 § 36) or "diakonos" (Excerpta ex Theodoto, § 16). It is impossible certainly to determine how Basilides conceived the relation of this Saviour to Jesus of Nazareth. Basilides himself (Strom. iv. 12 § 83) knows of an earthly Jesus and denies the principle of his sinlessness (see above). According to the account given by Irenaeus, the Saviour is said to have appeared only as a phantasm; according to the Excerpta ex Theodoto, 17, the Diakonos descended upon Jesus at His baptism in the form of a dove, for which reason the followers of Basilides celebrated the day of the baptism of Jesus, the day of the "epiphaneia". as a high festival (Clemens, Strom. i. 21 § 18). The various attempts at combination probably point to the fact that the purely mythical figure of a god-saviour (Heros) was connected first by Basilides with Jesus of Nazareth. As to what the conception of Basilides was of the completion of the process of redemption, the available sources tell us next to nothing. According to an allusion in Clemens, Strom. ii. 8 § 36, with the mission of the Saviour begins the great separation of the sexes, the fulfilment and the restoration of all things. This agrees with the beginning of the speculation of Basilides. Salvation consists in this, that that which was combined for evil is once more separated.
Among the later followers of Basilides, actual magic played a determining part. They hand down the names of the rulers of the several heavens as a weighty secret. This was a result of the belief, that whoever knew the names of these rulers would after death pass through all the heavens to the supreme God. In accordance with this, Christ also, in the opinion of these followers of Basilides, was in the possession of a mystic name (Caulacau = QAW LAQAW Jes. xxviii. 10) by the power of which he had descended through all the heavens to earth, and had then again ascended to the Father. Redemption, accordingly, could be conceived as simply the revelation of mystic names. In this connexion the name Abraxas and the Abraxas gems must be remembered. Whether Basilides himself had already given this magic tendency to Gnosticism cannot be decided.
Basilides, then, represents that form of Gnosticism that is closest to Persian dualism in its final form. His doctrine is most closely related to that of Satornil (Saturninus). From most of the other Gnostic sects, with the exception perhaps of the Jewish-Christian Gnosticism, he is distinguished by the fact that with him the figure of the fallen female god (Sophia Achamoth), and, in general, the idea of a fall within the godhead is entirely wanting. So far as we can see, on the other hand, Basilides appears actually to represent a further development of Iranian dualism, which later produced the religious system of Mani.
Accounts of the teaching of Basilides are to be found in all the more complete works on Gnosticism (see bibliography to the article Gnosticism). The original sources are best reproduced in Hilgenfeld, Ketzergeschichte des Urchristentums (1884), pp. 195-230. See also Krüger, article "Basilides," in Herzog-Hauck, Realencyklopadie, ed. 3.
 = Nimrod = Zoroaster, cf. Pseudo-Clement, Homil. ix. 3; Recogn. iv. 27.
 The materials are in Baur, Das manichäische Religionssystem (1831), p. 162, etc.
 Whether the myth of the creation of the first man by the angels, which recurs in many Gnostic systems, found a place also in the system of Basilides, cannot be determined with any certainty. Philastrius, however, says: hominem autem ab angelis factum asserit, while according to Epiphanus xxiv. 2, men are created by the God of the Jews.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)