According to Gregory Palamas,[1] Nikephoros was originally a Roman Catholic but travelled to the Byzantine Empire, where he converted to the Eastern Orthodox faith and became a monk at Mount Athos.
Like Theoleptos of Philadelphia, Nikephoros was a strong opponent of the union of the Eastern Orthodox and Roman Catholic Churches which was agreed to at the Council of Lyons in 1274.
[1] The main theme of Nikephoros’ spiritual writings in the Philokalia is nepsis (Greek: νήψις) which is usually translated as watchfulness or vigilance.
[2] For those inexperienced in prayer and spiritual self-control, the mind tends to wander and lapse into imagination.
Nikephoros described a method of breathing while praying to concentrate the mind within the heart in order to practice watchfulness.