Polycarp was a Christian writer of the first and second century martyred in the mid second century. It was said of him that he “…was instructed by the apostles, and was brought into contact with those who had seen Christ.” He was spoken of as having been taught directly by the Apostle John. His student, Irenaeus, wrote volumes (he has been mentioned on this site previously).
During his lifetime, it is clear that some churches had already departed from the form for the assemblies and the instruction given in the NT. The words and concepts translated into English for the terms elders, overseers, or presbyters and the Late Latin bishop, are all used interchangeably in the NT. But there was a distinction ready to be imposed and drawn; and it occurred early on.
In his one letter, Polycarp listed the duties of the overseers this way – “And let the presbyters be compassionate and merciful to all, bringing back those that wander, visiting the sick, and not neglecting the widow, the orphan, or the poor, but always ‘providing for that which is becoming in the sight of God and man;’ abstaining from all wrath, respect of persons, and unjust judgment; keeping far off from all covetousness, and quickly crediting [an evil report] against anyone, not severe in judgment, as knowing that we are all under a debt of sin.” He does not note any distinction between either men or duties.
From the same period, scholars have the writings of another disciple and writer named Ignatius. He was also said to have been taught of those who had seen Christ. Of the letters attributed to him, scholars doubt the authenticity of several, but do credit seven writings as being authentic. Ignatius died 48 years prior to the death of Polycarp. He too wrote of the duties of the elders, but had clearly identified the elevation of one of their number in several entries. The elevated office is listed as “the” bishop, or “the” elder, these men would later in time come to be known as a metropolitan, or as the Metropolitan Bishop.
Ignatius identifies the distinction between the one elder and the presbyters here in his letter to the Philadelphians. “See that you follow the bishop, even as Christ Jesus does the Father; and the presbytery, as you would the apostles.” He had earlier stated this in his letter to the Roman Christians, “Take heed then to have but one Eucharist. For there is one flesh of our Lord Jesus Christ, and one cup to show the unity of his blood; one altar; as there is one bishop, along with the presbytery and deacons, my fellow servants; that so whatever you do, you may do it according to [the will of] God.” Note the Romanism preferred by the translators in using the transliterated Greek and Latin word Eucharist.