(Νικηφόρος ὁ Γρηγορᾶς), one of the most important Byzantine historians, was probably born in 1295, in the town of Heralcleia Pontica, in Asia Minor. While he lived in his native town, his education was conducted by John, archbishop of Heracleia, but, having been sent to Constantinople, he was placed under the care of John Glycis, patriarch of Constantinople. [GLYCIS.] He learned mathematics and astronomy from Theodorus Metochita, the writer. At an early age Gregoras, who had taken orders, became acquainted with the emperor Andronicus I., the elder, who took a great fancy to him, and offered him the important place of Chartophylax, or keeper of the imperial archives, but the modest young priest declined the office, on the plea of youth. He afterwards, however, accepted several offices of importance, and in 1326 was sent as ambassador to the Kral, that is, the king of Servia. Gregoras was still very young, when he became celebrated for his learning. A dispute having arisen as to the day on which Easter was to be celebrated, Gregoras, in an excellent dissertation, proved that the system then adopted for computing that day was erroneous, and proposed another method. If it had not been for the fear which the clergy entertained of exciting the superstitious mob of Constantinople by a reform of the calendar, the computation of Gregoras would have been adopted by the Greek church. When pope Gregory XIII., 300 years afterwards, reformed the calendar, it ws found that the computation of Gregoras was qite right: the treatise which he wrote on the subject is still extant, and highly appreciated by astronomers. Being a staunch adherent of the elder Andronicus, Gregoras was involved in the fate of this unfortunate emperor, when he was deposed, in 1328, by his grandson, Andronicus III., the younger, who punished the learned favourite of his grandfather by confiscating his property. For a few years after that event Gregoras led a retired life, only appearing in public for the purpose of delivering lectures on various subjects, which were crowned wich extraordinary success. The violence of his language, however, caused him many enemies. In 1332 he pronounced funeral orations on the emperor Andronicus the elder, and the Magnus Logotheta, Theodorus Metochita, mentioned above. He opposed the union of the Greek and Latin churches proposed by pope John XXII., who had sent commissioners for that object to Constantinople. An excellent opportunity for exhibiting his learning and oratorical qualities presented itself to Gregoras, when the notorious Latin monk Barlaam came over from Calabria to Constantinople, for the purpose of exciting dissensions among the Greek clergy. Barlaam had reason to expect complete success, when his career was stopped short by Gregoras, who challenged the disturber to a public disputation, in which Barlaam was so completely defeated, that, in his shame and confusion, he retired to Thessaloneica, and never more appeared in the capital. The dissensions, however, occasioned by Barlaam had a most injurious influence upon the peace of the Greek church, and caused a revolution, which ended most unfortunately for Gregoras. Gregorius Palamas, afterwards archbishop of Thessalonica, espoused the dogmas of Barlaan he was opposed by Gregorius Acindynus, and hence arose the famous controversy between the Palamites and Acindynites. This quarrel, like most disputes on religious matters in the Byzantine empire, assumed a political character. Gregoras resolved to remain neutral: his prudence ruined him, because, as his violent temper was known, be became suspected by both parties. Palamas, having been condemned by the synod of 1345, the victorious Acindynites were going to sacrifice Gregoras to their suspicions, but he was protected by John Cantacuzenus, afterwards emperor, who during a long time had professed a sincere friendship for him. A short time afterwards the Acindvnites were condemned in their turn, and the Palamites became the ruling party; they were joined by John Cantacuzenus, and this time Gregoras did not escape the resentment of the victors, though his only crime was neutrality. Abandoned by Cantacuzenus, he was imprisoned in 1351. He was afterwards released; but his enemies, among whom his former friend Cantacuzenus was most active, rendered him odious to the people, and when he died, in, or probably after, 1359, his remains were insulted by the mob.