What the phrase actually describes
Apostolic succession sounds abstract until you have watched it happen. At the consecration of an Orthodox bishop, other bishops stand around the man, open the book of the Gospels over his bowed head, and lay their hands on him while the prayer is read. Those bishops were made bishops the same way, by men who were made bishops the same way, and so on backwards, out of living memory, through the centuries, to the apostles.
The Church has always insisted that this be done by more than one man. The first of the collection known as the Apostolic Canons says simply: "Let a bishop be ordained by two or three bishops." The fourth canon of Nicaea in 325 asks for all the bishops of the province where possible, and at minimum three meeting together with the written consent of those absent, with the ratification left to the metropolitan. Nobody may make himself a bishop, and no single bishop may make another one alone.
That detail matters more than it looks. A bishop is not a man who has acquired something and can pass it on privately. He is received by a college of bishops into a ministry that is not his, on behalf of a particular community that has asked for him. Even the canonical arithmetic is designed to prevent anything resembling a private transaction.
The laying-on of hands in the New Testament
The gesture runs through Acts and the pastoral epistles without ever being explained, in the way that habits people share are never explained. The eleven replace Judas by choosing Matthias (Acts 1:15-26). The apostles pray and lay hands on the seven (Acts 6:6). The church at Antioch fasts, prays and lays hands on Barnabas and Saul before sending them out (Acts 13:3). Paul and Barnabas appoint elders in every church (Acts 14:23), and Titus is told to appoint elders town by town (Titus 1:5).
Two verses to Timothy are the clearest. In the RSV: "Do not neglect the gift you have, which was given you by prophetic utterance when the elders laid their hands upon you" (1 Timothy 4:14), and "I remind you to rekindle the gift of God that is within you through the laying on of my hands" (2 Timothy 1:6). Something is described as given through hands. Timothy is warned not to be casual about giving it himself: "Do not be hasty in the laying on of hands" (1 Timothy 5:22).
None of this is offered as proof-texting. It is the ordinary texture of the apostolic churches, and the question is simply whether that texture was meant to continue after the apostles died, or whether it was a feature of the founding generation only.
What the second century took for granted
The generation immediately after the apostles answers that question without appearing to think it controversial. Writing from Rome to Corinth around the end of the first century, St Clement says that the apostles appointed their earliest converts as bishops and deacons, and gave directions that when those men died, other approved men should succeed to their ministry. He is not arguing for succession; he is appealing to it as something both churches already accept.
St Ignatius of Antioch, writing on his way to martyrdom around 107, assumes bishop, presbyters and deacons in each city as a matter of course, and tells the churches to do nothing pertaining to the Church apart from the bishop. Seventy years later St Irenaeus of Lyons, in the third book of Against Heresies, meets the Gnostic teachers by listing the bishops of Rome in order and pointing to Polycarp of Smyrna, who had been taught by the apostle John and whom Irenaeus had heard as a boy.
Honesty requires a qualification. In the New Testament the words for presbyter and bishop are sometimes used of the same men — compare Acts 20:17 with Acts 20:28, or Titus 1:5 with Titus 1:7 — and historians argue about how quickly the threefold pattern of bishop, presbyter and deacon became universal. Orthodoxy reads the New Testament vocabulary in the light of what the churches demonstrably did within a generation or two. A reader who finds that move too quick is raising a fair question.
What Orthodoxy believes is transmitted
The thing handed on is the apostolic ministry: authority to ordain other clergy, to preside at the Eucharist, to receive people into the Church and to reconcile them, to teach as an accountable witness of what the Church has always taught. When Christ breathed on the disciples and gave them the Spirit with the power to forgive sins (John 20:22-23), Orthodoxy understands him to be equipping a ministry that would outlast the men in that room.
Notice what this is not. The grace at work in a sacrament is Christ's, not the bishop's. He is not a reservoir that has been filled and from which a measure can be drawn; he is a steward, and the prayers of ordination say so. Nor is a bishop ordained in the abstract: he is ordained for a diocese, a named community of real people, and a bishop without a flock is an anomaly the canons struggle to describe.
It follows that succession is not a chain of magic. Nothing passes down it automatically in the way that voltage passes down a wire. What is given is a commission within the Church, and it is exercised inside the Church's life, under her canons, answerable to the other bishops and to the faithful who will notice soon enough if their bishop starts teaching something strange.
What is not transmitted
Personal holiness is not transmitted. This needs saying plainly, because a great deal of misunderstanding starts here. Judas was one of the Twelve and had been sent out to preach and to heal. Bishops in the Arian party had been consecrated by hands as properly as anyone. Nestorius was Archbishop of Constantinople. The iconoclast patriarchs held real sees by real ordinations, and several of them were learned and personally austere.
Correct teaching is not automatically transmitted either. The Orthodox Church has deposed, condemned and anathematised bishops who stood in the line, and has kept doing so. A bishop who begins teaching what the Church does not hold is not protected by the hands that were laid on him; the Church's response has been to remove him. Succession secures the office, not the man in it.
This is why it is wrong to speak as though the Orthodox claim were a claim about pedigree. Nobody is saved by being in a lineage. What the lineage does is much more modest: it means that there is a visible, traceable, accountable continuity between the community gathered in a hall in Kovan on a Sunday morning and the community that gathered in Jerusalem in the first century, and that the continuity can be checked.
The Protestant conviction: succession of doctrine
Many thoughtful Christians hold that what genuinely has to be handed on is the apostolic message, not the apostolic hands, and they have a text to hand. Paul writes to Timothy, in the RSV: "what you have heard from me before many witnesses entrust to faithful men who will be able to teach others also" (2 Timothy 2:2). Hands are not mentioned. Teaching is. A line of bishops that no longer teaches what the apostles taught, on this view, is a line that has ceased to be apostolic in the only sense that counts.
The argument is serious and it is not a dodge. Orthodox history supplies some of its best evidence: for several stretches in the fourth century the majority of sitting bishops in the East were Arian or semi-Arian, and the faith was being defended by a deposed and exiled Athanasius and by monks with no office at all. A reader who concludes from that episode that hands alone settle nothing has read the episode correctly.
It is also worth saying that this is not a Protestant idiosyncrasy. Many Protestant bodies, including Anglicans and several Lutheran churches, retain bishops and set store by continuity of office; and every Orthodox bishop would agree that the office is worthless if the teaching is abandoned. The disagreement is narrower and more precise than the usual shorthand suggests.
Why Orthodoxy holds the two together rather than choosing
Consider how Irenaeus actually argued. His opponents claimed a secret apostolic tradition passed to initiates. He did not answer by producing a lineage instead of a doctrine; he answered that the apostles' teaching is public, that anyone can go to Ephesus or Rome or Smyrna and find out what the church there has been taught continuously, and that the succession of bishops is what makes that check possible. Succession, for him, is the accountability of the teaching, not a substitute for it.
Put the other way round: a doctrine needs an address. If apostolic teaching is handed on by whoever has understood it rightly, the question of who has understood it rightly has no way of being settled except by each generation's judgement, and sincere people who read the same Bible reach different conclusions. If, instead, a visible community is charged with the teaching and can be held to it, the claim becomes checkable and the standard becomes public.
So Orthodoxy declines the choice. The hands without the faith produce an Arian bishop, and the Church deposes him. The faith without the hands produces a teaching with no one accountable for it, which in practice fragments. Held together, they amount to a single claim: the Church that hands on the apostolic faith is the same Church, continuously, and you can go and look at it.
There is one more strand. The bishop ordains, but he does not ordain in private. Historically an election involved the clergy and people of the diocese, and the congregation's acclamation, axios — he is worthy — still survives in the service as their part. The continuity Orthodoxy claims runs through a whole body, not only through a line of men.
Saying the Orthodox position plainly
Enquirers usually want to know what all this implies about other Christians, and they deserve a straight answer rather than a diplomatic one. The Orthodox Church holds that she is the Church founded by Christ and that the sacraments are given in her. That is not a recent hardening or a Russian peculiarity; it is the traditional position, and Fr. Seraphim Rose, an American convert from a Protestant family, stated it without softening.
In the Orthodox Church alone is grace given through the sacraments
Fr. Seraphim Rose, letter of 27 November 1980, quoted in Hieromonk Damascene, Father Seraphim Rose: His Life and Works, ch. 84 (St. Herman Press, 2003)
And saying plainly what Orthodoxy does not claim to know
In the very same letter, written to a catechumen troubled by Orthodox Christians calling her Protestant and Catholic relatives heretics, Fr. Seraphim set a limit that is as much part of the Orthodox position as the sentence above. He would not pronounce on where any individual stands before God. He added, in that letter, that he had met people whose lives were entirely changed by meeting Christ, and that he could not deny their experience because they were not Orthodox.
Two claims, then, and they do not cancel each other. The Church makes a definite claim about herself and about where the sacraments are given. She makes no claim at all about the eternal standing of the Christian down the road who loves Christ, reads Scripture daily, and has never once been told what an Orthodox bishop is for. Those are different questions, and confusing them has done a great deal of damage.
If you have read this far from a Protestant background, nothing here asks you to conclude that your pastor is a fraud or that your grandmother's faith was empty. It asks a narrower question: whether the community that Christ founded was meant to be visible and continuous, and if so, where that continuity is to be found. Come and see how it looks from inside before deciding. The doors in Kovan are open on Sunday mornings, and nobody will ask you to sign anything.
it is not for us to define the state of those who are outside the Orthodox Church
Fr. Seraphim Rose, letter of 27 November 1980, quoted in Hieromonk Damascene, Father Seraphim Rose: His Life and Works, ch. 84 (St. Herman Press, 2003)