Saint Nicholas Cabasilas was born in Thessaloniki in 1322, and was the nephew of Neilos Cabasilas, who was the Archbishop of Thessaloniki. His father's surname was Khamaetos, but he preferred to use his uncle's name - Cabasilas.
Nicholas received an excellent education, both at Thessaloniki and Constantinople, studying rhetoric, theology, philosophy, etc. For a time, he served as an advisor to Emperor John VI Cantacuzenos (reigned 1347-1354), who entrusted him with several important missions in the time of civil war (1341–1347) and religious strife. In the last year of his life, the Emperor abdicated and was tonsured as a monk with the name Joasaph. He remained in the renowned Manganon Monastery until his death. Nicholas seems to have become a monk at Manganon at the same time, and it is possible that he was ordained as a hieromonk.
He was a disciple of Saint Gregory of Sinai, and a supporter of Saint Gregory Palamas, both of whom were proponents of hesychasm (stillness), involving the unceasing prayer of the heart, which can lead to a vision of the Uncreated Light of Tabor. Nicholas took part in the Hesychast controversies of his time, which ended when the Council of 1351 proclaimed the teachings of Saint Gregory Palamas as Orthodox.
The fame of Nicholas rests mainly on his two books: Explanation of the Divine Liturgy, and Concerning the Life in Christ, which describes the Church's Holy Mysteries, divine grace, and perfection in the divine virtues.
In his writings Nicholas expounds the hesychastic (and Patristic) teaching that the life in Christ, which begins in this life, is perfected in the Kingdom. Sanctification comes only from Christ, but sanctity is achieved when our wills are in harmony with Christ's will.
Book 6 of Concerning the Life in Christ contains some very instructive comments on the Beatitudes. Nicholas points out that those who study and meditate on these sayings of Christ shall become truly happy. He compares the Beatitudes to "a ladder by which we may ascend to (the life of blessedness)."
The date of Nicholas's blessed repose is uncertain, but it probably occurred before 1391. If that is true, then he must have been aware of the fall of Thessaloniki to the Turks in 1387.
Saint Nicholas Cabasilas was glorified as a saint on July 19, 1983. The Troparion composed in his honor describes him as "a divine teacher, a wise interpreter of the dogmas of faith, and of the divine virtues."
As a divine teacher, a wise interpreter of the dogmas of faith,
and of the divine virtues, O Venerable Nicholas,
you shone forth in the world by your life and your word.
Therefore, Thessaloniki boasts of your glory,
lovingly keeps festival, and celebrates your most exalted memory.