Let those that minister aright be held worthy of double honour and especially those that labour in the word and teaching; (1 Tim: 17) because that they are not appointed of the bishops for (payment of) anything at all; wherefore they must needs be honoured with all godly honour, For when Moses served the altar worthily, God did grant unto his countenance a splendour greater than all. (Ex 33:9) And this did God make for a sign unto them that serve the altar aright in holiness, even as he. For he was the faithful presbyter, who laboured in the word and in doctrine and established the law for that obstinate people and bore their burden and their weeping and their irreverent murmuring wherewith they murmured against the Lord, and the curses that they uttered against Him. (Num 11:10) Yet was not all this a burden unto him because of the beauty of the altar whereof he was the minister and which was an image of the Word. Wherefore he was honoured more than any, in that he tasted of the sweetness of God ; he, the first that spake of the Church and gave unto her the form of the tabernacle, that by this fixed design the Church might be called to mind. For the tabernacle which followed him was an image of the Church. And not only did he make it, but he also set therein in order the ordinances of the sacred service, that he might teach us the fear of God that doth surround the altar, albeit we see it not. For he made bells round about the hem of the raiment of Aaron his brother, (Ex 28) that, when the chiefs at the holy place heard him enter the tabernacle, they might step aside, lest they should die. For every one that shall venture to approach the altar, without observing the law of God, shall die a wretched death, even as the sons of Eli, the priest of the Lord. For none that serveth the altar in impurity or with neglect shall die a good death. 
He saith also unto the priests which draw nigh unto the Lord, that they sanctify themselves, lest the Lord destroy certain of them. (Ex. 19:22) For this befell the sons of Aaron , when they sanctified not themselves according to the bidding of their father’s brother, to perform their priesthood in the fear of God. (Lev 10:2) For Moses said, “I fear and tremble, for this is the place wherein the Lord dwelleth”, (Ex 3:6) as He said unto Moses, “I will appear unto thee in this place, between the wings of the cherubim, and will speak with thee.” (Ex. 25:22) For a word went forth from His mouth saying, “No man seeth my face and liveth.” (Ex. 33:20)
David knoweth this when he saith, “Dreadful art thou, O God; who can stand before Thee?”(Ps. 80:3) And the prophet David never ventured to draw nigh unto the Lord or, like a priest, to offer sacrifice, albeit he longed so to do, as he saith, “I love Thy dwellings, O Lord of Hosts, and my soul longeth for the courts of the Lord. (Ps. 134:1,2) His desire to approach the altar and to be a priest was greater far than (his desire for) the glory of his kingdom. For by no means have all men authority to approach the altar, rather for him only whom the Lord hath chosen for this duty; and he must (then) perform his service in fear and trembling. For David had (himself) seen how Saul, who without right or authority made an offering, instead of a blessing, received therefor a curse and fell into great grief. For God took from him his glory when he ventured to approach the sanctuary, being but a layman, and to take upon himself the office of Samuel, the faithful priest. (1 Sam. 13:9-14) For this cause did God take from him his kingdom and gave it unto David, because that he reverenced the altar. 
He saw also the destruction which God performed upon Uzzah, because Uzzah did without authority put forth his hand and lay hold upon the ark of the covenant of the Lord. For as the calf which bore the ark caused it to lean aside, Uzzah laid hold upon it; wherefore the Lord destroyed him and he died forthwith before the Lord. (1Chr 13:9) And when David beheld that, his heart was oppressed and albeit he desired to bring the ark unto his house, yet durst he not, saying, How and in what manner should the ark of the Lord enter into my dwelling? (2 Sam 6:8) And when Dara received the ark, his state of poverty ceased and he became rich, as it is said, The Lord blessed the house of Dara the Chaldaean, and all that he had, because of the ark of the Lord. (2 Sam 6:12) For who shall even draw nigh unto an altar with little fear and be safe? 
King Uzziah also coveted the outward form of the priesthood, for verily it is a thing to be desired. (2 Chr 26:16) Yet wherefore do I call to mind a single man, that alone suffered through the Holy Ghost? Did not the most of the sixty myriads which followed Moses die through the Holy Ghost? As the Israelites said unto Moses, “We are become few and are perished,” (Num 17:12) because that the earth had swallowed up Dathan and Abiram with their men. This befell them because that they had desired the honour of the priesthood. Korah also and his multitude, in all two hundred men, died in wrath before the Lord, (Num 16:1) as it is written, “To him that hath shall be given, that he may have abundance; but from him that hath not, the little that he hath shall be taken away.” (Mat. 25:29) For God would teach us the fear that belongeth unto the altar and unto all the vessels that are upon the altar. It is said, The Lord spoke thus with Moses and Eleazar saying, “Take the brazen vessels, which have been brought before the Lord, from the midst of the men that were burned, because they had sanctified (them) with a sinful soul. Bring them before the Lord.” (Num 16:36-38) 
Wherefore he commanded them in every place, saying, “Reverence my holy places.” (Lev.19:30), For the Lord reproveth the priests also, saying, “They have defiled the Lord’s holy place and have turned aside from my law.” (Zeph 3:4) And in Ezekiel He saith, as one that is sad at heart because of the princes, “They build them houses beside the altar, wherein to eat and drink. For they have set their dwellings beside my dwelling and their wall standeth betwixt me and them, that they with their whoredom maybe put far from me.” (Ezek sept.) The wise Paul also doth blame such as these, saying, “Have ye no houses wherein ye may eat and drink, that ye should despise the church of God and put them to shame that have not?” (1 Cor 11:22) And again the holy Gospel saith, He made a scourge of cords and cast out all the sellers and buyers, saying, “Make not my father’s house a house of merchandise”, (John 2:15) teaching us thereby that God’s house is the church and the altar the table of the Lord, as He saith in the prophet Malachi, “Woe unto him that saith, ‘The table of the Lord is defiled.” (Mal I:7,12) And He saith, “Woe unto you also, ye scribes and Pharisees, because ye say, Whoso shall swear by the temple and altar, it is nothing; but whoso shall swear by the gold of the temple and by the offering which is upon the altar, he is thereby bound.” (Mat 23:16) Now no man may draw nigh unto the temple and the holy altar but those that have sanctified themselves as befits the holy place. He saith, “Fear and know that I am God”. (Lev 25:17) 
For this cause, O priest, it is given unto thee that thou have power over all this. Doth not God require of thee that thou shouldst be without sin? Wherefore keep thyself far from receiving and from presents, for thereby come sins. O thou levitical priest, wherefore dost thou sell or buy? ... May that not befall thee which is said, “Their souls are seized away through iniquity.” (Hos 4:8) When the priest doth evil, what then shall the people do? The priests are chosen that they may be more holy than the people and that unto them the offerings may be given, that they may be holy, praying for the people, entreating for their sins, even as Moses saith of them, that they are those whom the Lord God hath chosen. (Deut 11:5) And when the priest shall sin like the people, who than shall pray for them? For a people and priests that are impure, the same have no prayer which goeth up to God for the people, as it is said, “The Lord heareth not the prayer of the sinner.” (Prov 15:29) For ten times did the wrath of the Lord come upon the people in the desert, that he might root them out. But Moses prayed for them and the Lord turned away His wrath from them and had pity upon the sinful people, for a just man’s sake, because that he had not grieved the heart of God. 
So now none shall be made a priest but men of understanding, loving God, loving men, such as are able worthily to stand before the altar. For many in these times chose not the holy for the priesthood, by reason of their poverty, and (rather) they chose the rich that (live) without law, to entrust them with the Lord’s flock, though they be not faithful unto themselves; of whom the Lord saith, “I have given mine inheritance into their hands, yet have they done unto me no good, but have laid a heavy burden upon the aged.” (Is 47:6) Woe unto him that draweth nigh unto the altar being unclean. They have entrusted unto thee these men and have set thee over these offerings, as one in trust and as one that doth set in order, O levitical priest, that many may seek help of thee at God’s service and that thou mayest win the souls of them for whom thou shalt be answerable, as it is said, “He is answerable for all the flock.” (Ezek 34:10) Wherefore God hath placed the people under your feet, ye priests, ye great men in God’s house, as he saith unto the people, “Obey your chief men and submit yourselves unto them, for they it is that pray day and night for your souls.” (Hebr 13:17) If thou dost keep watch for the people and prayest for them, thou shalt surely redeem the souls of them whose offerings thou eatest. But if not and thou art slothful, how and in what way wilt thou give account of them? If thou be not found the intercessor for them in their troubles, then is it not meet that thou shouldst eat their offerings.
Wherefore art thou loaded with this great judgeship? Is it for the sake of shameful gain? Truly on account of this shameful gain many do become bishops, and many presbyters also and deacons likewise. And on account of such He saith, The priests which draw nigh unto God must keep themselves holy, that God destroy not some of them. (Ex 19:22) Why lookest thou upon the altar and the incense with irreverent eye? Why bindest thou thyself by these curses and these tears, while there be in the world many trades whereby thou mightest live and so be saved from this fearful punishment that befalleth them that devote themselves not worthily unto the service of the altar. Blessed is he that shall prove worthy to attain unto honour at the hand of the mighty and merciful Lord. Of such works (it is said) thus, I fear not to fall into the hand of the living God, (2 Sam24:14) and so again, Blessed is he that receiveth from Him a blessing . (Ps 24:5)Whoso therefore would belong unto the dread altar, let him be diligent, as is worthy of the holy place. If He had no mercy upon the sons of Eli the priest, because their father in his highpriestship had not trained them up aright, so that they should observe the priesthood, but rooted them out and likewise destroyed the priests’ town Nob with the edge of the sword, from man to woman and from young to old, they and their cattle, and not that only but also the men that bare the banners, so that the number was three hundred and fifty men of those that fell beneath the feet of Saul, (I Sam 22:18,19) as it is said, “I went forth from my dwelling in Shiloh, because of the sins of the priests and the iniquity of your fathers.” (Ps. 78:60) If He did this in the place where His name first dwelt and destroyed them, they and all their multitude, what then shall He do unto us, if we sin against the place of His holiness? Once already have I said, No man that hath served the altar in impurity hath died a happy death, but rather all that did despise the altar died a wretched, fearful death. The altar, that is to say, the offering, is a place of joy for whoso holdeth fast unto His laws, by reason of the fear that is His; but for him that is slothful He is destruction. If ye can not be humble, stand afar off, lest ye be burned; for that which is upon the altar is an unquenshable fire, as God hath said, “The fire of the altar shall not die out.” (Lev 6:9,12) If thou hast power to walk in the canons of the Apostles thou shalt attain unto like honour with them. But if thou have not the power, then flee afar off; for Amos saith, “When I beheld the Lord standing upon the altar, He said unto me, Smite the place of forgiveness, that the outer doors may be shaken. (Amos 9:1) By this place of forgiveness He meaneth not the (thing of) wood, but the servants that are about the place of forgiveness and stand at prayer by the place where sins are forgiven. It is said, “Teach the priests that they may teach the people”, (Deut 31:9) For whoso is not of the presbyters and deacons, the same is called people; wherefore the priest prayeth for the people. But the rest of the people also must pray for the priest, as it is written, “Give strength unto him whom thou hast prepared for us, that they be not found in sin.” (Ps. 68:28)
The priests must behave themselves according as the Apostles have ordained. In nothing blameworthy, married to one wife, vigilant, wise, orderly, of an understanding heart, apt to teach, not a lover of shameful gain, ordering well his house, faithful, true, pure, continent, constant in the right word, steadfast in doctrine. He shall not be double-tongued, neither have two weights and measures; eager to lend unto him that asketh, be it in a costly or in an abundant time; a father unto orphans, yea unto them he knoweth not, and unto widows, (yet) in all purity; who lifteth not up his eyes to behold any woman, nor turneth away his face from the poor, neither forgetteth them that are in prison but visiteth and serveth them according to his power; who is grieved for all the weak; respccteth not persons; hateth all sin, (but) loveth the righteous; reproving sinners and teaching them repentance; who receiveth not a gift, nor driveth out any man; who layeth no over-heavy burden upon them that despise him, who blesseth them that curse him, maketh complaint of no man but rather suffereth every oppression that befalleth him; not sullen; desiring not beauty of face; binding not upon the poor man beyond that his strength can bear; not resisting the rich; admonishing all that would be taught in humbleness of heart; approaching the altar not with pride but in humility, that is, regarding not himself as more than all the people but rather as one of them ; who receiveth all that come unto him; who keepeth watch over himself, not each night to defile his couch, when that same day he would perform the holy office. And if he is able, let him be continent, for that is better; but be he not able, let him not for that cause be a burden unto himself, because that many women and virgins and veiled brides have been entrusted unto him, and they come unto thee one by one and receive thy blessing. For that which is entrusted unto thee was not given (even) unto Moses, the greatest of the prophets, but unto Miriam his sister, which went before the women, while he himself led only the men. But thou art leader both for the men and women. Wherefore watch thyself in all things, knowing that unto whom much is entrusted, of him shall much be required. For they come not unto thee but unto Christ, whom thou servest, and they come not unto thee that thou shouldest set a value on their ornaments but rather that they should take account of thy faith. For he that keepeth his eyes that they behold not the face of women, his heart remains pure from defilement. It is said, “Mine eye is pure and innocent, so that I see not any evil thing.” (Hab 1:13) He whose eyes are pure, his heart also is pure, as it is said, “Blessed are the pure in heart, for they shall see God.” (Mt 5:8) He that looketh on no woman, his heart is not defiled. Look not upon the face of a woman, O priest, for they have been entrusted unto thee that thou mightest guard thyself. Say as thou prayest, Avert mine eyes, that they behold not vanity, (Ps 119:37) as one that knoweth that the house entrusted unto thee is the house of heaven, and that it is the church upon earth, whereof Jacob saith, “This is the house of God, this is the gate of heaven.” (Gen28:17) For all the angels which come from before God do come first unto the church and glorify the house of God that is upon earth.
If thou wouldest learn the truth, hear, that I may teach thee how thou mayest honour the church with all reverence. For she is builded in heaven in the form that Moses planned, when he built the tabernacle according to the form which he had seen upon mount Sinai. (Ex 25:9) Give heed to the reverence which belongeth unto the holy place wherein thou doest service. Hear how God commanded Moses, “Ordain for thy brother Aaron that he come not at all times within the veil before the altar, lest he die. For in a cloud upon the altar will I show myself and will speak with thee.  (Lev 16:2) And if He forbade Moses and Aaron, who did minister, to come within the veil at all times as they wished, how much the more them that with little reverence do talk in the holy place or that without shame dispute over the altar vessels or steal the first fruits of the altar? For, because the Lord standeth upon the altar, so are they (i.e. the altar vessels) spiritual and neither silver nor gold nor stone nor wood; even as the bread and wine, before they are raised upon the altar, are bread and wine, yet, after that they are raised upon the altar, are no more bread and wine, but the life-giving body and blood of God, so that they that communicate therein die not, but live eternally. So (also) is the altar; and be it of wood or stone or gold or silver, it is no (more) mortal, as its former substance, but liveth for ever and is spiritual; for the living God standeth thereon. As He testified concerning Moses and Aaron, that they were holy in His priesthood, and as it is said that bells of gold should be hanged upon the garment of Aaron, that the angels who guard the altar might hear their noise; so now shall the presbyters be holy with all holiness, the more especially because the holy body and life-giving blood hath been distributed unto them. And if the mount whereon He once did stand, to give the law unto the people, be turned to a thing better and more holy, as this is testified by the seventy elders of the sons of Israel, saying, “We beheld the place where stood the God of Israel, and the place beneath His feet was as bricks of sapphire or carbuncle, like in its holiness to the firmament of heaven.” (Ex 24:10) And if the stone was thus singularly transfigured and made thus beautiful, how much more the altar, the sanctuary whereon He daily standeth and the place wherein His feet appear to us. And if it was not entrusted to Moses and Aaron to enter into this place whensoever they would, albeit the Holy Ghost testified of them saying that Moses was holy and Aaron, in His priesthood; if (then) these two holy men ventured not to transgress the Lord’s commandments, coming before Him in fear and trembling, humbling themselves before Him with prayers and much fasting and great purity and making before them a noise with the bells of gold that hung at the openings of their garments, so that the chiefs that were round about the holy altar should hear their sound as they entered in and were hid from view, that they might not die, if haply they should enter suddenly, for the altar can never remain without an angel, nay not for an instant or the twinkling of an eye, therefore must they (the clergy) do the service in purity; and with the pure and holy incense, wherewith the presbyter doth cense about the altar, must he surround himself, for shame before the Holy Ghost, even as holy virgins are ashamed. For the altar that is set up in heaven before the Lord is the Holy Ghost, reasonable and speaking and knowing who it is striveth for him upon earth. And he (i.e. the Holy Ghost) ordereth that none impure nor any adulterer nor drunken nor who hath drunk overmuch wine nor a hater of men nor an usurer nor slanderer shall draw nigh him. For all the servants of the place where is the body of Christ must be without sin, as the eagles. For He hath said, “In the place where the carcass is, there will the eagles be gathered.” (Mt 24:28)
Condensed from: The Canons of saint Athanasius the Apostolic: canons 1-10

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