Theophylact of Ohrid:

94) {4}. Perhaps you would like to know who these church fathers are? Methodios, who adorned the Pannonian diocese by becoming the Archbishop of Moravia, and Cyril who was great in his knowledge of the heavenly philosophy, and even greater in his knowledge of the Christian lore, and knew the nature of all things that actually exist ...

{5}. Because the Slavic and Bulgarian people did not understand the Scripture as written in Greek, the saints deemed this loss the greatest. They found a reason for their unconsolable grief in the fact that the lamp of the scriptures was not shining in the dark place [II Pet., 1: 19] of the Bulgarians. They grieved, suffered, and denied this earthly life.

{6}. And so, what were they to do? They turned to the Comforter [Acts, 2: 2] and begged of him this grace: to invent an alphabet that might contain the wildness of the Bulgarian language. They begged him for the ability to translate the divine scriptures into the tongue of that people. And in truth, giving themselves up to strict fast and enduring prayer, to mortification of the flesh and to humbling unto meekness of the spirit, they received that for which they yearned ...

(95) {7}. And so they received spiritual grace sure as the dawn [Hos., 6: 3], and light rose in the darkness for the upright [Ps., 96: 11; 111: 4], and the joy that comes from these things dispelled their grief. After they received the coveted gift, they invented the Slavic alphabet, translated the divinely-inspired Scriptures from the Greek into Bulgarian and took care to impart divine knowledge to the best of their disciples. And many drank of the source of learning and from among them the chosen leaders were Gorazd, Clement, Naum, Anguelarii and Sava.

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(96){10}. After that the Pope saw those of the party accompanying the holy men. The teachers testified that they had sufficient experience with Slavic letters and were adorned with a pious life. Some were ordained priests, some deacons, and others subdeacons. And although great Methodios kept refusing and would not consent, the Pope ordained him Bishop of Moravia in Pannonia because he thought it unjust to deny ecclesiastical rank to one who had earned it by his deeds ...

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{13}. Thus death brought Cyril honour from both the the most divine pope and from God. Methodios, for his part, having lost his companion and fellow toiler, who has been a true brother to him in flesh and in God, gave his heart to sorrow ...

(98) {14}. And when the time came for Methodios to start on his way to Pannonia, and he had finally to raise his eyes towards the bishopric in that land, he hugged his brother'�s tomb, uttered many times the name Cyril, bewailed his own desolation in the flesh, evoked Cyril�'s power of intercession on their behalf, and set out for Moravia with his disciples. And when he arrived there, he became a true bishop, manifesting in himself such qualities as are listed by Paul in his character of the bishop [1 Tim., 3, 2-7; Tim., 1, 7-9] and outshone all with his teaching. He did not bury his talent [Mat., 5: 18], and did not sell the grace of his spiritual gifts [Acts, 8: 18; 1 Tim., 3: 3; Tit., 1: 7]. Nor did he turn his power into a source of luxury [Tit., 1: 9] but made all fellow communicants in goodness by equally spreading the light of the word [Mat., 5: 45]. He, who even before his bishopric was such a zealous teacher and preacher that he subjected himself to danger, now that office had been entrusted to him, and he had received the pledge and knew the charge of an apostle, �Woe to me if I do not preach the Gospel!� [1 Cor., 9: 16], how could he not but commit himself to teaching, devote himself with heart and soul, all day long, to the word of God alone, which was sweeter than honey in his mouth [Ps., 18: 11; 118: 103]?

{15}. He did not cease from giving daily instructions to Prince Rostislav of Moravia, nor from educating his soul in the divine commandments. He also instructed and educated the ruler of all Pannonia, named Kotsel, so that he may never have fear of the Lord [Ps., 118: 120] and, detained and restrained by his bridle, would avoid all wickedness.

Great Methodios did not cease from lavishing the love of the word on the Bulgarian prince Boris, who lived during the days of the Byzantine emperor Michael, whom he had already made is spiritual son.

{16}. This Boris was altogether possessed of sane reason and was inclined to goodness. It was under him that the Bulgarian people began to (99) receive divine baptism. When those saints, Cyril and Methodios, saw that there were many believers and that many children of God were being born through water and spirit [John., 3: 5], but that they were wholly deprived of spiritual food, they invented the alphabet, as we said, and translated the Scriptures into Bulgarian so that the newborn children of God could have enough divine nourishment ... Thus the Bulgarian people, freed of the Scythian deceit, came to know the straightest road, Christ [John, 14: 6]. And thus at the eleventh hour they entered God'�s vineyard through the grace of He who had beckoned all labourers [Mat., 20: 6; Gal., 1: 15; Tim., 1: 9]. And so the call went out to that people in the 6377th year of the creation of the world.

...

{18}. The heretics [i.e. Franks, promoting the filioque clause], being thus defeated by the power of the word and of truth, did only what they could, or, rather, what they were sent to do (100) by their father who was a murderer from the beginning [John, 8: 44]. He bragged of his wickedness, and tortured the saint with all kinds of evils and temptations. Deceiving him with cunning, they had fully won for their teaching Svetopolk, prince of Moravia after Rotislav, who was but a coarse prince, unable to understand goodness. How could a slave of physical pleasures, wallowing in the mire of his filthy deeds [Prov., 7: 18] keep from submitting himself to those, who opened before him every door of bodily lust, instead of to Methodios, who condemned the bitterness of pleasure seeking, which poisons the soul. That which Eunomius, founder of the Anomian heresy, created in order to draw to himself more disciples, the insensible Franks also embraced. They forgave sinners everything, even the without toil and diligence on their part, for the sake of mere agreement with their doctrine. They allowed their converts to lead a life of vice in order to secrue the success of thier perverse teaching by exchanging rubbish for dirt, being worthy only to trade with such treasures in which the goods are obnoxious and the price repellant.

{19}. Because of that, Svetopolk was perverted by them, since they would allow him anything. He paid little heed to the words of Methodios, whom he treated as an enemy. To the sinner piety is shameful [Sirach., 1: 25]. Nevetheless, the teacher did everything he could to speak fairly to the prince and to caution him against all manner of terrors. On one hand, he proved the correctness of his teaching through the divine Scriptures, and bade Svetopolk trust them as the source for life and salvation [Isa., 12: 3]. The Lord Himself teaches us that life consists in searching the Scriptures [John, 5: 39], and Isaiah admonishes us to draw water not from the swamp of heresy, but from the wells of salvation [Isa., 12: 3]. On the other hand, the teacher told him that should he join the heretics, he would condemn not only himself, but also all those under his power. He would easily become vulnerable to enemies, and be vanquished, for lacking chastity, even if one flourishes for a time, eventually leaves wither and fall. The teacher Methodios prophesied that this would befall Svetopolk after his own death, and the saint'�s prophecy came true.

{20}. While Methodios still lived, Svetopolk did not reveal the schemings of his heart, even though he did have a basilisk, and was hiding and nursing it within the eggs of an asp [Isa., 59: 5]. ... (101) But when the saint died a flurry of evil whirled about and no longer hid its hideous face with a mask or veil. Like a harlot, it acted shamelessly and stirred persecution against the orthodox. Then it was that God punished the prince.

{21}. Methodios foretold his own death within three days. He did so to uphold the abundant advice he had given the prince. Thus, when his prophecy came true, it showed him as truly as prophet with a gift to foresee the future. It revealed that his doctrine was spiritual and inspired by the Lord.

Something funny :

A picture from a Macedonian history textbook. The textbook proclaims the Bulgarian rebels Petar Deljan and Tihomir for "Macedonians". However, the picture contains part of the manuscript of Byzantine historian John Skylitzes, who has written above their heads "Boulgaroi" = Bulgarians.