Detail of mediaeval fresco of St. Clement in the Lower church of San Clemente
From the Catholic Encyclopedia:
Pope Clement I (called CLEMENS ROMANUS to distinguish him from the Alexandrian), is the first of the successors of St. Peter of whom anything definite is known, and he is the first of the "Apostolic Fathers". His feast is celebrated 23 November. He has left one genuine writing, a letter to the Church of Corinth, and many others have been attributed to him.
According to Tertullian, writing c. 199, the Roman Church claimed that Clement was ordained by St. Peter (De Praescript., xxxii), and St. Jerome tells us that in his time "most of the Latins" held that Clement was the immediate successor of the Apostle (Illustrious Men 15). St. Jerome himself in several other places follows this opinion, but here he correctly states that Clement was the fourth pope. The early evidence shows great variety. The most ancient list of popes is one made by Hegesippus in the time of Pope Anicetus, c. 160 (Harnack ascribes it to an unknown author under Soter, c. 170), cited by St. Epiphanius (Haer., xxvii, 6). It seems to have been used by St. Irenæus (Haer., III, iii), by Julius Africanus, who composed a chronography in 222, by the third- or fourth-century author of a Latin poem against Marcion, and by Hippolytus, who see chronology extends to 234 and is probably found in the "Liberian Catalogue" of 354. That catalogue was itself adopted in the "Liber Pontificalis". Eusebius in his chronicle and history used Africanus; in the latter he slightly corrected the dates. St. Jerome's chronicle is a translation of Eusebius's, and is our principal means for restoring the lost Greek of the latter; the Armenian version and Coptic epitomes of it are not to be depended on. The varieties of order are as follows:
1. Linus, Cletus, Clemens (Hegesippus, ap. Epiphanium, Canon of Mass).
Linus, Anencletus, Clemens (Irenaeus, Africanus ap. Eusebium).
Linus, Anacletus, Clemens (Jerome).
2. Linus, Cletus, Anacletus, Clemens (Poem against Marcion),
3. Linus, Clemens, Cletus, Anacletus [Hippolytus (?), "Liberian Catal."- "Liber. Pont."].
4. Linus, Clemens, Anacletus (Optatus, Augustine).
Writing of St. Clement
From St. Clement we have an Epistle to the Corinthians, written c. 96 AD. Here is a selection:
The Church of God which sojourneth in Rome to the Church of God which sojourneth in Corinth, to them which are called and sanctified by the will of God through our Lord Jesus Christ. Grace to you and peace from Almighty God through Jesus Christ be multiplied.
By reason of the sudden and repeated calamities and reverses which are befalling us, brethren, we consider that we have been somewhat tardy in giving heed to the matters of dispute that have arisen among you...
[...]
Forasmuch then as these things are manifest beforehand, and we have searched into the depths of the Divine knowledge, we ought to do all things in order, as many as the Master hath commanded us to perform at their appointed seasons. Now the offerings and ministrations He commanded to be performed with care, and not to be done rashly or in disorder, but at fixed times and seasons. And where and by whom He would have them performed, He Himself fixed by His supreme will: that all things being done with piety according to His good pleasure might be acceptable to His will. They therefore that make their offerings at the appointed seasons are acceptable and blessed: for while they follow the institutions of the Master they cannot go wrong. For unto the high priest his proper services have been assigned, and to the priests their proper office is appointed, and upon the levites their proper ministrations are laid. The layman is bound by the layman's ordinances. Let each of you, brethren, in his own order give thanks unto God, maintaining a good conscience and not transgressing the appointed rule of his service, but acting with all seemliness.
Source: Early Christian Writings
Further, in that same epistle is found a prayer which Msgr. Duchesne suggest to be "an excellent example of the style of solemn prayer in which the ecclesiastical leaders of that time were accustomed to express themselves at meetings for worship" (Origines du culte chret., 3rd ed., 50; tr., 50):
[Grant unto us, Lord,] that we may set our hope on Thy Name which is the primal source of all creation, and open the eyes of our hearts, that we may know Thee, who alone abidest Highest in the lofty, Holy in the holy; who layest low in the insolence of the proud, who settest the lowly on high, and bringest the lofty low; who makest rich and makest poor; who killest and makest alive; who alone art the Benefactor of spirits and the God of all flesh; who lookest into the abysses, who scanest the works of man; the Succor of them that are in peril, the Savior of them that are in despair; The Creator and Overseer of every spirit; who multipliest the nations upon earth, and hast chosen out from all men those that love Thee through Jesus Christ, Thy beloved Son, through whom Thou didst instruct us, didst sanctify us, didst honor us.
We beseech Thee, Lord and Master, to be our help and succor. Save those among us who are in tribulation; have mercy on the lowly; lift up the fallen; show Thyself unto the needy; heal the ungodly; convert the wanderers of Thy people; feed the hungry; release our prisoners; raise up the weak; comfort the fainthearted. Let all the Gentiles know that Thou art the God alone, and Jesus Christ is Thy Son, and we are Thy people and the sheep of Thy pasture.
Thou through Thine operations didst make manifest the everlasting fabric of the world. Thou, Lord, didst create the earth. Thou that art faithful throughout all generations, righteous in Thy judgments, marvelous in strength and excellence, Thou that art wise in creating and prudent in establishing that which Thou hast made, that art good in the things which are seen and faithful with them that trust on Thee, pitiful and compassionate, forgive us our iniquities and our unrighteousnesses and our transgressions and shortcomings.
Lay not to our account every sin of Thy servants and Thine handmaids, but cleanse us with the cleansing of Thy truth, and guide our steps to walk in holiness and righteousness and singleness of heart and to do such things as are good and well pleasing in Thy sight and in the sight of our rulers.
Yea, Lord, make Thy face to shine upon us in peace for our good, that we may be sheltered by Thy mighty hand and delivered from every sin by Thine uplifted arm. And deliver us from them that hate us wrongfully.
Give concord and peace to us and to all that dwell on the earth, as Thou gavest to our fathers, when they called on Thee in faith and truth with holiness, [that we may be saved,] while we render obedience to Thine almighty and most excellent Name, and to our rulers and governors upon the earth.
Thou, Lord and Master, hast given them the power of sovereignty through Thine excellent and unspeakable might, that we knowing the glory and honor which Thou hast given them may submit ourselves unto them, in nothing resisting Thy will. Grant unto them therefore, O Lord, health peace, concord, stability, that they may administer the government which Thou hast given them without failure.
For Thou, O heavenly Master, King of the ages, givest to the sons of men glory and honor and power over all things that are upon the earth. Do Thou, Lord, direct their counsel according to that which is good and well pleasing in Thy sight, that, administering in peace and gentleness with Godliness the power which Thou hast given them, they may obtain Thy favor.
O Thou, who alone art able to do these things and things far more exceeding good than these for us, we praise Thee through the High priest and Guardian of our souls, Jesus Christ, through whom be the glory and the majesty unto Thee both now and for all generations and for ever and ever. Amen.
Source: Early Christian Writings
The Basilica
Within Rome, surely one of the most beautiful, if not also one of the most liturgically interesting, of the Roman basilicas is that which is dedicated to St. Clement, San Clemente.
The relics of St. Clement are beneath the high altar of the basilica and today, on his feast, they are exposed for veneration and carried in solemn procession through the neighbouring Roman streets.